The right hand of bin Laden, the Number Two in "Al-Qaeda" was trained at the secret base of the Russian secret services on Caucasus, the former Lieutenant Colonel of the Russian Federal Security Service (FSB) Alexander Litvinenko told the Polish Rzeczpospolita newspaper. Until the end of 1998, Litvinenko had served in several top-secret units that specialized in struggle against the terrorist and the mafia organizations.

Litvinenko claims that Ayman al-Zawahiri, who headed at that time the terrorist organization "Al-Jihad al-jadid" (it was formed from the Egyptian emigrants - activists of "Al-Jihad" and "Al-Jamaah al-Islamiyah"), in 1998 secretly stayed on the territory of Russia.

Up to the beginning of 1998, the process of merging of the two most radical Islamic organizations – "Al-Jihad al-jadid" and "Al-Qaeda" was completed. Al-Zawahiri became the second person in the hierarchy of the Osama bin Laden's "Al-Qaeda". In February 1998, being together in Afghanistan, they have created the World Islamic Front for Jihad Against Jews and Crusaders. However, at that time the Western secret services yet did not pay any special attention to al-Zawahiri's activity (several years prior to that, he freely visited the USA, and several countries of the Western Europe). The hunt for him, as well as for his fellows in arms began only after the explosions in the American embassies in Kenya and Tanzania, in August, 1998.

Only then the CIA analysts with the help of the Egyptian and Israeli colleagues managed to restore retrospectively a part al-Zawahiri's "activity schedule" for seven months prior to the attacks in East Africa. As it was discovered, since January till the end of July, 1998, he personally supervised the preparation for the terrorist attacks in Kenya and Tanzania.

For this purpose al-Zawahiri had left the territory of Afghanistan several times, in particular traveling to Sudan (in the middle of May, 1998). In parallel, he paid a lot of attention to strengthening "Al-Qaeda's" ties with secret services of Khartoum and Tehran.

Although our American and Israeli sources do not know about al-Zawahiri staying in Russia, they have supplied us with some other interesting details. According to this information, in the first half of 1998, leaders of "Al-Qaeda" tried in every possible way to increase the level of coordination with terrorist groups worldwide. For this purpose the leaders of many such groups and cells of "Al-Qaeda" were invited to Afghanistan. Getting close to the large-scale attack on the USA, Osama bin Laden and Ayman al-Zawahiri have organized a "congress" of the adherents from all over the world. It took place on June, 24, at the capital of the talibs - Kandahar, in southern Afghanistan. Among the visitors were the representatives of the Balkan countries, the Middle East and Africa, and even of the radical Islamic groups from the republics of the former USSR. The Uzbeks and the Chechens were especially outstanding. Besides them, the Kazakhs, the Kyrgyz, the Dargins, the Lakks, and the Tatars had also secretly arrived to Kandahar. All of them came here separately, using sideways. A week prior to the beginning of the conference, a group of well-armed al-Zawahiri's assistants had left by jeeps in the direction of Herat. Following the instructions of their patron, in the town of Koh-i-Doshakh they met three unknown men that arrived from Russia via Iran. The latter called themselves by Muslim names, despite the fact that the two of them had a clearly Slavic appearance. After their arrival in Kandahar, the 'guests' split up. One of the "Russians" was directly escorted to al-Zawahiri, and he did not participate in the conference.

Later on, this 'Russian guest', for almost six years disappeared out of the secret services' sight. He reappeared only in 2004. On February, 13, in the capital of Qatar the car of the ex-president of the Chechen Republic Zelimhan Yandarbiev was blown up.

Couple of days after his death, the authorities of the United Arab Emirates detained two Russian citizens. They turned to be the officers of the secret services. For the last three months they had been working in the embassy of Russia in Doha. After Yandarbiev's assassination these two Russians together with several other of their fellow citizens have hastily left Qatar. Having found out all this, investigators have carefully studied video and photo materials made by the counterspies during the last months on a course of supervision over the Russian diplomatic mission. The results were surprising not only for the Qatar's secret services, but also for their Western colleagues. It appeared that at the end of November, 2003, the embassy was visited by the above-mentioned "Russian", who met al-Zawahiri in the summer of 1998 in Kandahar.

Complaining of persecution, in 2000 Mr Litvinenko fled to the UK where he sought, and was granted, asylum. But after settling in an unnamed London suburb, the former spy - who had a wife and teenage son - continued to behave as if on the run, constantly changing his contact details.

Well aware of the methods of those who work in the shadowy intelligence underworld, he met contacts at busy, public locations.

The Times newspaper reported in May 2005 that someone had tried to push a pram loaded with petrol bombs through his front door.

Despite all this, in an interview four years ago, Mr Litvinenko said: "I believe Russia will rise again and that I will manage to return again to the motherland and Moscow."

Appearing alongside high-profile opponents of Mr Putin, Mr Litvinenko continued to make allegations about his former bosses.

Perhaps most notably, he alleged that al-Qaeda number two Ayman al-Zawahiri was trained by the FSB in Dagestan in the years before the 9/11 attacks.

He also denounced the war in Chechnya as a crime, called for Russian troops to be withdrawn, and said compensation should be paid to Chechens.

One of his friends - and one of a number of Russian exiles now settled in Britain - is Akhmed Zakayev, a former Chechen commander living under asylum in London.

The two men lived on the same street in London, it has been reported.

In the past, Russia has asked Britain to stop exiles such as Mr Berezovsky and Mr Zakayev making what it calls "slanderous statements" about the Russian regime.

Their dream was a poison which would kill a man instantly but which could not be found in a corpse's blood during the post-mortem examination. For years, the secret poison laboratory of the Soviet-era biologist Grigory M Mairanovski, founded on the orders of Lavrenti Beria in 1938, researched deadly substances. The moment came when Mairanovski and his team felt that, by deceiving even experienced medical experts, they had achieved their dream.

It happened when German prisoners-of war who had been killed with Mairanovski's poison were immediately transferred to the Sklifasovskii emergency clinic in the heart of Moscow. The Sklifasovskii medics were unable to find the poison - and concluded that the German POWs had in fact died of natural causes.

The Mairanovski laboratory was closed in 1946 following the replacement of Lavrenti Beria by Vsevolod Merkulov as head of the NKVD. But poisons continued to be used intermittently throughout modern Soviet and post-Soviet history, indicating that the tradition of toxicological assassination was never completely abandoned.

It was some times pursued via proxies. Georgi Markov, a Bulgarian writer and journalist with the BBC World Service, died in London in September 1978 after apparently being injected with poison from the tip of an umbrella.

Yuri Shchekochikhin, a Russian journalist (deputy editor-in-chief of Novaya Gazeta) and member of the Duma (parliament), died on the night of 2-3 June 2003 after returning from a business trip to the city of Ryazan where he had sought to investigate a furniture-store corruption scandal involving high-ranking intelligence officials.

His illness was first described by Moscow doctors as allergy but when he lost his hair, and the skin on his face changed its structure, it became obvious that his body was reacting to a strong, unidentifiable poison. Doctors were unable to save him; he died within a few days.

For a few years, Shchekochikhin's Novaya Gazeta colleagues tried to discover the real reasons for his death, and sent tissue-samples to London for further investigation. In the event it was not possible to identify the poison which killed Shchekochikhin, though his editor-in-chief Dmitri Muratov has no doubts that this was the cause of death.

Another poisoning attempt affected journalist Anna Politkovskaya (later shot dead by an unknown assassin on 7 October 2006). At the first news of the Beslan school siege in September 2004 she rushed to the airport to seek a seat on flight in the direction of the north Caucasus. In the end she got a ticket for a flight to Rostov-on-Don. Aware of all possible dangers she refused to eat and drink on board. Only at the end of the flight did she request a glass of water. She fainted after the plane landed, and for days doctors struggled to save her. She had been poisoned, perhaps by two secret-service agents who had followed her onto the plane.

The most famous poisoning case involved the Ukrainian opposition leader (now president) Viktor Yushchenko. A few months before the presidential election in 2004 he was hospitalised suffering stomach pains. Soon his face began to change, and a mask of lesions and blisters disfigured the Ukrainian politician's previously youthful looks. Numerous examinations held by laboratories in the Britain, Austria, the Netherlands and Germany confirmed that Yushchenko was poisoned purposely by a poisonous substance called dioxine.

In April 2002 the Russian secret services used a poison in order to liquidate one of the most dangerous Chechen warlords, Omar ibn-Khattab. He died within five minutes after opening a letter said to be written by his mother. It was delivered by a Chechen fighter recruited by the Russian secret services as their agent.

Events in Moscow's Dubrovka theatre in October 2002, when 900 spectators were taken hostage by Chechen fighters, further demonstrate how much the Russian secret services are fond of employing poison-gas substances. After getting inside the building, members of the special forces used an unidentified narcotic gas to subdue the terrorists. But it affected hostages too. 129 of them died, all but two from the adverse effects of the gas.

The case of Alexander Litvinenko, the former secret service (FSB) agent now in a London hospital after being poisoned in a restaurant with a dose of the metal thallium, is no different. Before and after his flight to London, the colonel had made enemies in the Russian government and intelligence services.

At first he accused his bosses of organising an attempt to kill émigré businessman Boris Berezovsky, himself a strong critic of president Putin. Litvinenko's book on the mysterious explosions of apartment blocks in Moscow and other cities in September 1999 which killed more than 300 people angered his enemies even more. Litvinenko had no doubts that the explosions - which helped propel Russia into its second Chechen war, and were followed a year later by the election of Vladimir Putin to the presidency - were organised by the FSB to convince public opinion that war was essential to curb Chechen terrorism.

The Kremlin's allies in Moscow deny that the FSB could be involved in an attempt to poison Litvinenko with thalium. In their view the incident helps Boris Berezovsky, who will now use it in his propaganda campaign against the Kremlin. Gennadi Gudkov, a Duma member and retired KGB colonel, acidly praised Berezovsky's talent as a director of theatrical spectaculars.

But Kremlin critics such as Sergei Kovalev, or former Yukos executive and KGB general Alexei Kondaurov, do not exclude anothrer possibility: that former colleagues of Alexander Litvinenko had themselves had enough of his criticism and activities.

As with so many elements in the melancholy trail of Russian deaths in the last sixteen years, the truth will be hard to find. But the method, the symptoms, and the mysterious circumstances in which a poison was used in London all indicate that the tradition of Dr Mairanovski's laboratory has not been forgotten.

The mysterious death of a former Russian spy living in exile in London turned into an unprecedented public health scare yesterday when it emerged that he had been deliberately poisoned by a major dose of radioactive material.

Further traces of the substance were found at a sushi restaurant and at a central London hotel where Alexander Litvinenko met a number of people before falling ill, and at his home in the city.

He was killed by polonium 210, a rare radioactive isotope which is so toxic that there may never be a postmortem examination of Mr Litvinenko's body, for fear of causing further deaths.

Police and security sources said they had never encountered such an extraordinary death. "Nothing like this has ever happened before," said one Whitehall source. "It is unprecedented, we are in uncharted territory." One priority last night was to establish who has access to polonium 210 anywhere in the world.

Government ministers meanwhile, are said to be "dreading" the possible repercussions of a public inquest into Mr Litvinenko's death, at which they expect his associates to make damning accusations against the Russian government.

Last night health officials were contacting up to 100 people - hospital staff and relatives - who came into contact with the former spy during his three weeks at two London hospitals, so they can be screened for contamination. The home secretary, John Reid, also convened Cobra, the government's emergency planning committee, to discuss the situation.

The Health Protection Agency (HPA) said the risk to hospital staff was extremely low, as alpha radiation from the ex-agent's body would need to be inhaled, swallowed, or enter an open wound before causing harm. Normal hospital practices should have prevented this. Nor would anybody be at risk just because they had been close to Mr Litvinenko.

But the agency said it could not assess the level of risk to the public who had visited locations which had been contaminated with the substance. Professor Roger Cox, director of the HPA's centre for radiological, chemical and environmental hazards, said there was insufficient information to make such an assessment. Last night police were refusing to say how much of the substance was found at the hotel and restaurant, or at Mr Litvinenko's house in Muswell Hill, north London.

Radiation from the polonium was first detected in Mr Litvinenko's urine hours before he died on Thursday night. There is no antidote to the substance and the HPA said that such a large dose would always kill once ingested. Scientists are trying to use computer models, based on analysis of Mr Litvinenko's urine, and the apparent damage to his organs over the last three weeks, to work out when he may have been poisoned.

While Scotland Yard say they are treating his death as suspicious, they are not describing their investigation as a murder inquiry. One possibility being considered is that Mr Litvinenko poisoned himself.

Deputy Assistant Commissioner Peter Clarke, head of Scotland Yard's counter-terrorism command, which is conducting the investigation, said: "We continue to carry out a thorough investigation. There will also be an extensive examination of CCTV footage."

Enemies of the Russia's president, Vladimir Putin, blamed him - insisting the poisoning bore the hallmarks of an assassination by Mr Litvinenko's former colleagues from the FSB, a successor to the KGB. Mr Litvinenko fled to Britain six years ago after revealing an alleged plot to murder Boris Berezovsky, a multimillionaire businessman also in exile in the UK.

On November 1, he met Mario Scaramella, an Italian academic, at a sushi restaurant. Mr Scaramella showed him two emails, obtained by the Guardian, which warned "Russian intelligence officers speak more and more about necessity to use force" against critics of Russia including Mr Berezovsky and Mr Litvinenko.

Yesterday Mr Litvinenko's associates, many of them employees of Mr Berezovsky, produced a statement which they said was made by Mr Litvinenko last Tuesday, in which he blamed Mr Putin for his impending death.

"The howl of protest from around the world will reverberate, Mr Putin, in your ears for the rest of your life," he is said to have declared. "May God forgive you for what you have done, not only to me but to beloved Russia and its people."

Mr Putin brushed aside such claims yesterday, telling a press conference: "There is no ground for speculation of this kind. A death of a man is always a tragedy and I deplore this and send my condolences to the family."

Some of Mr Putin's aides went further, hinting at an expatriate plot to discredit the Russian government. "I am far from being a champion of conspiracy theory," said Sergei Yastrzhembsky, Mr Putin's chief envoy to the EU. "But it looks like we are facing a well-orchestrated campaign or a plan to consistently discredit Russia and its leader."

The Foreign Office confirmed last night that officials had discussed Mr Litvinenko's death with the Russian ambassador at a meeting yesterday afternoon, and had asked Moscow for any information which would assist Scotland Yard with their inquiries.

The death bed statement by Alexander Litvinenko blamed Russian President Vladimir Putin for the poison he believes took his life. But will we ever know with certainty who was responsible?

While the Health Protection Agency says Mr Litvinenko was poisoned with the radioactive substance polonium-210, the question of who was responsible persists.

The former spy's two meetings in central London on 1 November, in Piccadilly and Mayfair, may hold the key to the identity of his killer.

Friends of the 43-year-old have blamed the Russian security service (FSB), as Mr Litvinenko accused it of many abuses, including the bombing of a block of flats in 1999, killing 300 people.

Others had linked his sickness directly to another focus of his criticisms, former KGB agent Putin.

Any involvement has been dismissed by the Kremlin as "nonsense", a sentiment echoed by Russia's foreign intelligence service.

The matter is now in the hands of Scotland Yard, which is investigating the case as an "unexplained death".

Security analyst Glenmore Trenear-Harvey, who met Mr Litvinenko several times, said the media focus on the Kremlin was "lazy" and bore the hallmarks of a John Le Carre novel.

"We have to put this in a historical context," he said.

"Litvinenko's last job within the FSB was heading up the anti-corruption unit and he discovered a lot of corruption there and made a lot of enemies within the KGB."

When Yeltsin broke the KGB into different agencies such as the FSB and the SVR, the majority of its members stayed on but some went into the Duma and a third group went into legitimate business, he said.

But a "murky bunch" went into what was known as the Russian mafia.

"My own belief, and this is speculation, is that it's not inconceivable that Anna Politkovskaya in her search for murderers within the Russian bank system discovered the contract killings were these former KGB people.

"She was killed and if Litvinenko indeed was privy to her investigations then it could well be that they will emerge as his killers."

Although the sophisticated nature of the poison suggested it could have come from the state, there was no motive, he said.

"There was no benefit to Putin or Russian intelligence services to have a highly publicised operation like this."

And despite the continued claims linking Putin, diplomatic relationships between the UK and Russia were unlikely to be affected, he said.

Alex Pravda, an expert in Russia foreign policy and a member of international analysis organisation Chatham House, believes it is too early to say who was responsible.

"There's a lack of clarity in all this. It's a matter of speculation and I think we have to wait until there's better evidence," he said.

And the lack of coordination between Russian government and other agencies made it difficult to point the finger with any certainty, he said.

What has characterised the Litvinenko case from the start has been the way one explanation has been quickly replaced by another.

It was thallium. No, it was radioactive thallium. No, it was a cocktail of drugs. No, it was a mystery object. Now polonium-210 has been identifed.

Given the days of uncertainty about what killed him, the matter of who killed him may never be resolved.

Anti-terrorist detectives are poised to fly to Russia and Italy in an effort to solve the fatal poisoning of the Russian dissident Alexander Litvinenko.

But as John Reid, the home secretary, said the police inquiry had been upgraded from an "unexplained" to a "suspicious" death, experts voiced doubt at the theory that anyone acting alone could have used the isotope polonium 210 to kill Mr Litvinenko. One scientist said polonium 210 would only kill so quickly if combined into a "designer toxin" with another isotope, beryllium, in a complicated process that would require state sponsorship. Such a process was used by Britain in early atomic weapons in the 1950s.

"No individual could do this," said John Large, an independent nuclear consultant. "What you are talking about is the creation of a very clever little device, a designer poison pill, possibly created by nanotechnology. Without nanotechnology you would be talking about a fairly big pill, a pea-sized pill. Either way you are looking at intricate technology which is beyond the means and designs of a hired assassin without a state sponsor."

He said the likely poison pill that killed Mr Litvinenko would have to have been manufactured in a special laboratory over two or three weeks and then used very quickly - possibly within 28 days - because the half-life of the isotope polonium is only 138 days.

Senior police officers are drawing in experts from the International Atomic Energy Authority, and from the Atomic Weapons establishment at Aldermaston. Every option is being considered, from Kremlin involvement to the theory that Mr Litvinenko's work in the anti-corruption unit of the FSB, Russia's MI5, created enemies with the means and knowledge to assassinate him.

The government's emergency planning group, Cobra, has met at least six times in the last few days. Police are studying hours of CCTV tapes to trace Mr Litvinenko's movements on and before November 1, when it is likely he received the dose of radiation that killed him. Officers may travel to Russia to interview Andrei Lugovoi and Dimitri Kovtoun, who met Mr Litvinenko in the Millennium hotel on November 1, and to Italy to speak to Mario Scaramella, who met him at the Itsu restaurant in Piccadilly.

"If we need to go to Russia and Italy we will do that at the appropriate time," one police source said yesterday. Mr Kovtoun, who denies involvement, said he was going for radiation tests, because of concerns over his own contamination. One man police may speak to is a former KGB general with links to the Dignity and Honour group of retired KGB officers.

The man is named in a document passed by Mr Scaramella to Mr Litvinenko as the ringleader of a group which could be planning to kill both men. He is understood to have left Moscow on Friday for an unknown destination.

The home secretary refused to be drawn on the police investigation yesterday. Meanwhile more than 300 people who were in the Millennium Hotel, in Grosvenor Square, London, and Itsu, in Piccadilly, on November 1 have contacted the NHS and the Health Protection Agency is following up the calls. Several have been asked to supply urine samples.

Mr Litvinenko's home in north London, where traces of alpha radiation from polonium 210 have been found, was still being examined yesterday.

The investigation into the death of former Russian spy Alexander Litvinenko gathered pace dramatically yesterday as it emerged that a number of British Airways aircraft that fly between Moscow and London have been contaminated with radioactive material.

Two BA Boeing 767s were grounded at Heathrow following tests ordered by Scotland Yard, and a third aircraft was being tested in Moscow after its pilot was warned not to take off.

Last night the airline appealed to around 800 passengers to come forward. They flew on four flights between London and Moscow in the days either side of Litvinenko's poisoning on November 1.

However, the Guardian understands that the airline is scrambling to contact up to 33,000 passengers and 3,000 of its own staff who flew on the aircraft, on 10 different routes, since October 25. The aircraft are known to have been used for a total of 220 flights.

The airline said that only "very low traces" of the substance had been discovered on the Boeing 767s and the risk to public health was low. Passengers concerned about their health should call NHS Direct, it said.

It is thought Litvinenko, 43, was not a passenger on any of the jets - he had been granted British citizenship after claiming asylum following his decision to become a whistleblower about the alleged activities of the Russian security services.

Aviation industry sources suggested other individuals connected to the police investigation had travelled on the aircraft. The police are particularly interested in a flight from Moscow to London on October 25. It is known Litvinenko met two Russian contacts, Andrei Lugovoi and Dmitri Kovtun, at the Millennium Hotel in London's West End on November 1, the day he fell ill.

Mr Lugovoi, a former KGB bodyguard who now runs a security company in Moscow, has said that he flew in the day before with his family and friends to attend a Champions League football match between Arsenal and CSKA Moscow and for a series of business meetings. As Litvinenko lay dying, Mr Lugovoi insisted he had been framed by someone who wished him to appear to be the poisoner.

British intelligence sources increasingly suspect that Alexander Litvinenko, the former spy killed with a radioactive poison, was the victim of a plot involving "rogue elements" within the Russian state, the Guardian has learned.

While ruling out any official involvement by Vladimir Putin's government, investigators believe that only those with access to state nuclear laboratories could have mounted such a sophisticated plot.

Police were last night closing in on a group of men who entered the UK among a large crowd of Muscovite football fans. The group of five or more arrived shortly before Mr Litvinenko fell ill and attended the CSKA Moscow match against Arsenal at the Emirates stadium on November 1. They flew back shortly afterwards. While describing them only as witnesses, police believe their presence could hold the key to the former spy's death.

The widow of Alexander Litvinenko has launched a blistering attack on William Hague and David Cameron, accusing them of sabotaging the inquest into her husband's murder and hiding the Russian state's role in his death.

Marina Litvinenko said she was "utterly dismayed" after a coroner on Friday upheld an application by Hague to keep crucial evidence from the inquest secret.

Sir Robert Owen reluctantly agreed to exclude material which suggested Russia's state agencies were behind Litvinenko's cold-war style killing.

Owen also agreed to suppress documents that examined whether UK officials could have done more to prevent his murder.

A furious Mrs Litvinenko said on Friday: "The effect of today's ruling is to protect those responsible for the murder of a British citizen on the streets of London, and to allow the Russian government to shield behind a claim for secrecy made by William Hague with the backing of prime minister David Cameron."

She said there had been "increasing signs over the past year" that the government was moving to strike what she called "a secret political deal with the Kremlin".

She cited increasingly warm recent meetings between Hague and his Russian counterpart, Sergei Lavrov, and Cameron's talks on Syria last week with Vladimir Putin in the Russian beach resort of Sochi.

Afterwards the two leaders announced that Russia and the UK were resuming intelligence co-operation.

The former Labour government severed all contacts with Russia's FSB spy agency in 2007 after concluding it had played a leading role in Litvinenko's assassination. Putin is the agency's former chief.

Mrs Litvinenko added: "This is a very sad day, a tragedy for British justice which has until now been respected around the world, and a frightening precedent for all of those who have been trying so hard to expose the crimes committed by a conspiracy of organised criminals who operate inside the Kremlin."

In his ruling (pdf), Owen said the inquest scheduled to take place later this year might now result in an "incomplete, misleading and unfair" verdict.

The coroner said he would consider inviting Theresa May, the home secretary, to hold a public inquiry instead. The inquiry could hear the sensitive evidence buried by Hague in secret sessions.

On Friday Mrs Litvinenko said that since the inquest had effectively abandoned its search for the truth, she had therefore written to the coroner asking him to initiate a public inquiry within five days.

The inquiry could begin on 2 October 2 – the date originally set for the inquest. Owen, who is a judge, could preside over it.

Litvinenko died in November 2006 after two former KGB agents – Andrei Lugovoi and Dmitry Kovtun – allegedly slipped radioactive polonium into his tea at London's Millennium hotel. The Kremlin has refused to extradite the two spies, who have both vigorously denied Litvinenko's murder.

Mrs Litvinenko's lawyer, Ben Emmerson QC, had previously accused Hague of attempting to stage a cover-up and of placing Britain's trade interests with Moscow ahead of justice.

Both Hague and Cameron were shamelessly "dancing to the Russian tarantella", he told a pre-inquest hearing.

Litvinenko's close friend Alex Goldfarb said it was now apparent that Hague was indeed hiding evidence in the case in order to appease the Kremlin.

"It's obvious: the government are trying to protect their relations with Putin. They have their reasons.

"They want Russian co-operation and investment. But in this case it's being done at the expense of justice."

Goldfarb said it was practically meaningless to soldier on with an inquest if it could no longer examine the role of Russia's spy agencies, nor damning evidence indicating that the polonium used in the murder plot came from Russia.

He added: "They [Hague and Cameron] appear more concerned about chemical weapons in Syria than polonium spread around the streets of London."

In his ruling, the coroner said the secret evidence held by the British government "does establish a prima facie case as to the culpability of the Russian state in Mr Litvinenko's death".

This evidence will now not be revealed. Owen made clear his unhappiness with this situation and admitted it made it difficult for him to carry out the "full, frank and fearless investigation" he originally promised.

Litvinenko's widow and other interested parties now have 14 days to challenge the coroner's decision. But they have little chance of success – not least because they have been kept in the dark as to what the secret evidence includes.

Hague's lawyers have shown "samples" of the controversial material in closed-door hearings held over several days.

National newspapers and the BBC had joined forces to oppose Hague's secrecy application and on Friday expressed their dismay at the ruling.

Jan Clements, a lawyer acting for the Guardian and other media groups, said: "It would mark a low point in open justice if evidence concerning the responsibility for and preventability of the killing of Litvinenko were only heard in a secret hearing."

Hague applied for a public interest immunity certificate (PII) on 7 February. He argued that if sensitive evidence were revealed it might damage the UK's "national security and/or international relations".

Critics complained this wording was excessively vague. The coroner did eventually reject a part of Hague's PII claim, but the subject was redacted and is shrouded in mystery.