The head of Porton Down appears to have contradicted claims by Boris Johnson about the poisoning of a former spy, Sergei Skripal.

In an interview, the foreign secretary secretary talked about the scientific analysis of the Novichok nerve agent that was used. And he seemingly confirmed that the Porton Down defence research laboratory had “no doubt” that the substance was made in Russia.

However, Porton Down’s chief executive has now said that scientists have “not identified the precise source”.

You can read FactCheck’s long read about the case here.

Mr Johnson’s claims were made to German TV channel Deutsche Welle, while reiterating the British government’s allegations against Russia.

The interviewer asked him: “You argue that the source of this nerve agent, Novichok, is Russia. How did you manage to find it out so quickly? Does Britain possess samples of it?”

During the course of a long response, Mr Johnson appeared to suggest that scientists from the UK’s military laboratory were adamant that the Novichok was Russian-made.

He said: “I genuinely think Russia is an incredible country, a fantastic place, and it pains me to see the way things have got between us. So, I’m genuinely distressed by what has happened. But when I look at the evidence; I mean, the people from Porton Down, the laboratory…”

“They have the samples?” the interviewer interjected.

“They do,” replied Mr Johnson. “They do. And they were absolutely categorical and I asked the guy myself, I said, ‘Are you sure?’ And he said there’s no doubt.”

Mr Johnson’s comments do not appear to match with further remarks by the head of Porton Down himself.

Speaking yesterday, Gary Aitkenhead said: “We were able to identify it as Novichok, to identify that it was military-grade nerve agent.”

But he added: “We have not identified the precise source, but we have provided the scientific info to government who have then used a number of other sources to piece together the conclusions you have come to.”

Aitkenhead said that identifying the source would require “other inputs”, explaining: “It is our job to provide the scientific evidence of what this particular nerve agent is, we identified that it is from this particular family and that it is a military grade, but it is not our job to say where it was manufactured.”

The apparent contradiction has already been leapt on by Labour. Shadow home secretary, Diane Abbott, said: “I don’t understand where he got that information from.”

And Labour MP Chris Williamson said: “Boris Johnson is your Foreign Secretary and he just lied to justify our country’s foreign policy.”

Meanwhile, Sky News quotes an unnamed source in the Foreign Office who said Mr Johnson “misspoke”.

But this is not the only time the government has made this claim. The Russian embassy in London has highlighted a tweet by the Foreign Office last month. The tweet said that Porton Down had “made clear” that the Novichok nerve agent was “produced in Russia”.

The tweet has now been deleted, with the Foreign Office explaining that it had been “truncated and did not accurately report our Ambassador’s words”.

In a statement today, the Foreign Office backed Mr Johnson’s remarks by suggesting he had simply been referring to the identification of the nerve agent itself – rather than its source.

A spokesperson told FactCheck today: “The Foreign Secretary was making clear that Porton Down were sure it was a Novichok – a point they have reinforced. He goes on in the same interview to make clear why based on that information, additional intelligence and the lack of alternative explanation from the Russians, we have reached the conclusion we have.

“What the Foreign Secretary said then, and what Porton Down have said recently, is fully consistent with what we have said throughout. It is Russia that is putting forward multiple versions of events and obfuscating the truth.”

The Foreign Office had previously explained: “This is only one part of the intelligence picture. As the Prime Minister has set out in a number of statements to the Commons since 12 March, this includes our knowledge that within the last decade, Russia has investigated ways of delivering nerve agents probably for assassination – and as part of this programme has produced and stockpiled small quantities of Novichoks; Russia’s record of conducting state-sponsored assassinations; and our assessment that Russia views former intelligence officers as targets.”

What should we read into it all?

Gary Aitkenhead’s comment may be seen as undermining the government’s allegations against Russia.

However, it is worth noting that the government has always maintained that it’s case is multi-faceted. Chemistry is only part of the story.

Professor Alastair Hay told us: “My reading is that Gary Aitkenhead was simply reaffirming what Porton had said previously about the identity of the agent. He was making sure that the laboratory’s role is clear. He pointed out the UK Government was using other intelligence evidence it had to point the finger of blame at Russia.

“But I think it is good that Aitkenhead did the reaffirmation. It keeps Porton above the fray and recognised for its scientific ability.

“Unless Porton had had a prior sample from the facility where the Novichok was made it would have been difficult to identify the source. If the environmental samples had had other ingredients from the production process in them this could have helped identify how it was made and thus help to narrow down facilities. But in the absence of that prior sample pointing a finger would be unsound.”

Professor Andrea Sella told FactCheck: “This is only partly about the chemistry… It strikes me that the Russian government is doing everything it can to cast doubt on everything. They’ve repeatedly undermined Porton Down, for example by suggesting that it might have actually made and delivered the agent. Now they leap on this statement which is very clear and very simple – the chemistry is Novichok; there is additional information from other sources that corroborates the idea that the stuff came from Russia. The demands from the Russians that the UK share its information are a transparent attempt to get the UK to reveal its intelligence information.”

“Let’s face it, there is no plausible alternative scenario. It’s about the wider pattern – over and over inconvenient Russians have been bumped off, in the UK and elsewhere. Their behaviour fits with a long standing bait and switch pattern to confuse and obfuscate.”

We have no way of verifying what Porton Down scientists may have told Boris Johnson behind closed doors; nor do we know what he was intending to refer to in his comments.

However, the question put by the interviewer specifically referred to Russia – as did Mr Johnson’s preceding comments.

Therefore, we think people might reasonably have assumed he was claiming that Porton Down had scientific evidence to show the Novichok was made in Russia – a claim that has proved to be wrong.

At best, this means his comments were sloppy and ham-fisted. At worst, they were wrong and misleading.

The statements from Porton Down do not necessarily change the government’s overall evidence base particularly. After all, we knew all along that chemistry was only part of the story.

The statements reaffirm the importance of strong intelligence. But, as of yet, the government has not elaborated on what intelligence it has – or released any of it. </s> The Foreign Office has deleted a post on its Twitter feed stating that British scientists had established the Novichok nerve agent used in the Salisbury poisoning came from Russia.

Foreign Secretary Boris Johnson has come under fire after an announcement on Tuesday that Porton Down scientists had not verified the source of the chemical believed to have been used in the March 4 attack on Sergei and Yulia Skripal.

The tweet, issued on 22 March, said: “Analysis by world-leading experts at the Defence Science and Technology Laboratory at Porton Down made clear that this was a military-grade Novichok nerve agent produced in Russia.”

Explaining the deletion of the tweet, a Foreign Office spokesman said it had been an inaccurate summary of comments made by the UK’s ambassador to Russia, Laurie Bristow, at a briefing in Moscow.

READ MORE: Duke of Edinburgh in ‘good spirits’ after major hip operation

Referring to Dr Bristow as “HMA” - Her Majesty’s Ambassador - the spokesman said: “A full transcript and video of the briefing have been available on GOV.UK since 22 March.

“An HMA Moscow briefing on 22 March was tweeted in real time by @UKinRussia and amplified by @foreignoffice, to explain what happened in Salisbury to as wide an audience as possible. One of the tweets was truncated and did not accurately report our ambassador’s words. We have removed this tweet.”

READ MORE: Salisbury poisoning: Porton Down can’t verify nerve agent is Russian

In an interview on German TV on 20 March when he was asked why the UK believed that Russia was the source of the nerve agent, Mr Johnson said: “The people from Porton Down, the laboratory, they were absolutely categorical. I asked them that myself. I said ‘Are you sure?’. He said ‘There’s no doubt’.”

Labour leader Jeremy Corbyn said Mr Johnson either had information that he had not shared with the laboratory or it was a “bit of exaggeration” and called for a “responsible” approach to the situation.

Mr Corbyn said: “He claimed categorically - and I think he used the words 101% - that it had come from Russia. Porton Down have not said that, they said that they’ve identified it as Novichok, they cannot identify the source of it.

“Either the Foreign Secretary has information that he’s not sharing with Porton Down or it was a bit of exaggeration. I don’t know which it is, but I think we need a responsible, cool approach to this.”

Russia’s proposal for a new, joint investigation into the poisoning was voted down at the international chemical weapons watchdog at The Hague last night. Russia has accused Britain of blocking access to an investigation being carried out by the Organisation for the Prohibition of Chemical Weapons. Britain earlier said Russia’s call for an inquiry with the UK was “perverse”.

Russia lost the vote by 15 votes to six, while 17 member states abstained. China, Azerbaijan, Sudan, Algeria and Iran were among the countries that backed Russia’s motion. </s> Mr Johnson made the comments after the chief executive of the Porton Down military facility admitted there was no proof linking the Novichok nerve agent used in the March 4 attack on Sergei and Yulia Skripal to Russia. Asked why the UK believed that Russia was the source of the nerve agent, Mr Johnson said: "The people from Porton Down, the laboratory, they were absolutely categorical. I asked them that myself. I said 'Are you sure?'. He said 'There's no doubt'."

Commenting on Mr Johnson's interview, a Government spokesman said: "The Foreign Secretary was making clear that Porton Down were sure it was a Novichok - a point they have reinforced. "He goes on in the same interview to make clear why based on that information, additional intelligence and the lack of alternative explanation from the Russians, we have reached the conclusion we have. "What the Foreign Secretary said then, and what Porton Down have said recently, is fully consistent with what we have said throughout. It is Russia that is putting forward multiple versions of events and obfuscating the truth." The Foreign Office also deleted a tweet insisting the novichok used in the Salisbury attack was definitely "produced in Russia". The tweet on March 22, said: "Analysis by world-leading experts at the Defence Science and Technology Laboratory at Porton Down made clear that this was a military-grade novichok nerve agent produced in Russia."

Labour leader Jeremy Corbyn has accused Mr Johnson of "exaggeration" over the evidence that Russia was to blame for the Salisbury poisoning. Speaking during a local election campaign visit to Watford, Mr Corbyn said: "He claimed categorically - and I think he used the words 101% - that it had come from Russia. Porton Down have not said that, they said that they've identified it as Novichok, they cannot identify the source of it. "Either the Foreign Secretary has information that he's not sharing with Porton Down or it was a bit of exaggeration. I don't know which it is, but I think we need a responsible, cool approach to this.

"We need to get to the source of this to prevent it ever happening again." Shadow home secretary Diane Abbott challenged the Foreign Secretary to explain his earlier comments. She said: ”It seems Boris Johnson misled the public when he claimed that Porton Down officials confirmed to him that Russia was the source of the nerve agent used in the Salisbury attack.

"Those officials have made it clear they cannot identify its source, and are not able to definitively say it came from Russia or elsewhere. "Boris Johnson is supposed to represent Britain on the world stage, but time and again he has shown he is unable to do so responsibly." Explaining the deletion of the tweet, a Foreign Office spokesman said it had been an inaccurate summary of comments made by the UK's ambassador to Russia, Laurie Bristow, at a briefing in Moscow. Referring to Dr Bristow as "HMA" - Her Majesty's Ambassador - the spokesman said: "A full transcript and video of the briefing have been available on GOV.UK since 22 March. "An HMA Moscow briefing on 22 March was tweeted in real time by @UKinRussia and amplified by @foreignoffice, to explain what happened in Salisbury to as wide an audience as possible. One of the tweets was truncated and did not accurately report our ambassador's words. We have removed this tweet." </s> In a major embarrassment to the UK establishment, the chief scientist from the UK's Porton Down military laboratory facility, Gary Aitkenhead, told Sky News that they had been unable to prove that the novichok nerve agent used to poison Sergei and Yulia Skripal came from Russia.

"We were able to identify it as novichok, to identify that it was military-grade nerve agent," Aitkenhead said. "We have not identified the precise source, but we have provided the scientific info to government who have then used a number of other sources to piece together the conclusions you have come to."

The chief scientist said that establishing the Novichok's origin required "other inputs," some of which are intelligence based and which only the government has access to.

Aitkenhead added: "It is our job to provide the scientific evidence of what this particular nerve agent is, we identified that it is from this particular family and that it is a military grade, but it is not our job to say where it was manufactured."

Oh good, at least Europe did not expel most Russian diplomats based on a Colin Powellesque assumption that since Russia is the only possible source of Novichok, so it must be. Oh wait...

Of course, this humiliation to the official narrative that Putin was clearly behind the assassination attempt all along also begs the question: whose job is it to say where the Novichok came from?

That said, it was also noted that the nerve agent involved required "extremely sophisticated methods to create, something only in the capabilities of a state actor," and that there is no known antidote to Novichok - nor was any administered to either of the Skripals.

Aitkenhead would not say whether the Porton Down facility had manufactured or maintained stocks of Novichok - long rumored to be the case.

"There is no way anything like that could have come from us or left the four walls of our facility," said the chief.

News of the UK's inability to trace the origin of the Novichok comes as a chemical weapons watchdog, the Organisation for the Prohibition of Chemical Weapons (OPCW) is set to hold an executive council meeting in The Hague on Russia's request.

Skripal and his daughter Yulia were poisoned four weeks ago in Salisbury. Russia has insisted on access to the pair.

Russia's Ambassador to the UK, Alexander Yakovenko, says that London's reluctance to share information on the March 4 poisoning of the former double agent and his daughter has led Moscow to suggest that London authorities actually perpetrated the crime.

“Our British colleagues should recall that Russia and the United Kingdom are members of the OPCW which is one of the most successful and effective disarmament and non-proliferation mechanisms," said Russian politician Vasily Shulgin. "We call upon them to abandon the language of ultimatums and threats and return to the legal framework of the chemical convention, which makes it possible to resolve this kind of situation."

“We have very serious suspicion that this provocation was done by British intelligence,” Yakovenko told Russia's NTV channel - adding however that Moscow had no direct proof, but that the UK's behavior constitutes strong circumstantial evidence in support of their theory.

Following the Skripal poisoning, the UK and several of its allies responded by expelling Russian diplomats - with the Trump administration kicking 60 Russians out of the country, and the UK expelling 23. Russia returned "fire" with the expulsion of several foreign diplomats, and a demand that Britain scale back its diplomatic mission in Russia - affecting over 50 jobs.

Yulia's condition is said to have improved significantly last week, and she is now conscious and talking. Meanwhile, Sergei Skripal reportedly remains unresponsive in critical condition. </s> London (AFP) - The British military facility analysing the nerve agent used to poison a spy said on Tuesday it could not prove the substance was made in Russia, as Russian President Vladimir Putin put his hopes in a meeting with the world's chemical weapons watchdog.

Gary Aitkenhead, chief executive of the Porton Down defence laboratory, told Britain's Sky News that analysts had identified the substance as military-grade Novichok, the word used for a category of nerve agents developed in Soviet times.

But he added: "We have not identified the precise source."

"It is our job to provide the scientific evidence of what this particular nerve agent is, we identified that it is from this particular family and that it is a military grade, but it is not our job to say where it was manufactured," Aitkenhead said.

He added that "extremely sophisticated methods" were needed to create the nerve agent, and that was "something only in the capabilities of a state actor"

Following his remarks, a British government spokesman said Porton Down's identification of Novichok was "only one part of the intelligence picture".

"This includes our knowledge that within the last decade, Russia has investigated ways of delivering nerve agents probably for assassination -- and as part of this programme has produced and stockpiled small quantities of Novichok; Russia's record of conducting state-sponsored assassinations; and our assessment that Russia views former intelligence officers as targets," he added.

Former double agent Sergei Skripal, who has lived in Britain since a spy swap in 2010, and his daughter Yulia have been in hospital since March 4 after the poisoning that London and its major Western allies have blamed on Russia.

The first use of chemical weapons in Europe since World War II has chilled Moscow's relations with the West, as both sides have expelled scores of diplomats.

Britain has also suspended high-level diplomatic contact with Moscow.

Moscow has denied any involvement in the incident, with Russian Foreign Minister Sergei Lavrov on Monday suggesting that the British government may be behind the poisoning to distract attention from problems around Brexit.

Aitkenhead would not comment on whether Porton Down had developed or keeps stocks of Novichok, but he dismissed claims the agent used to poison the Skripals had come from the site.

"There is no way anything like that could have come from us or left the four walls of our facility," he said.

The Organisation for the Prohibition of Chemical Weapons (OPCW), the world's chemical watchdog, will meet Wednesday to discuss Britain's allegations that Russia was responsible for the poisoning, according to documents released on Tuesday.

The OPCW said Russia had asked for the meeting, which Putin said was aimed at putting an end to the ongoing dispute.

"We hope that during those discussions a full stop will be placed on (the issue of) what happened," he said during a visit to the Turkish capital Ankara.

The meeting request came after Moscow received and analysed samples of the Novichok agent used in the attack.

The confidential gathering will start at 10:00 am (0800 GMT) at the OPCW's headquarters in The Hague.

"We hope to discuss the whole matter and call on Britain to provide every possible element of evidence they might have in their hands," Russia's ambassador to Ireland, Yury Filatov, told reporters ahead of the OPCW meeting.

"Russia is interested in establishing the whole truth of the matter," he said.

But Britain's foreign ministry accused Russia of requesting the meeting to undermine the organisation's investigation.

"This Russian initiative is yet again another diversionary tactic, intended to undermine the work of the OPCW in reaching a conclusion," the ministry said in a statement.

"Of course, there is no requirement in the Chemical Weapons Convention for the victim of a chemical weapons attack to engage in a joint investigation with the likely perpetrator," it said. </s> Boris Johnson is facing questions over a conversation he recounted with Porton Down officials about the Salisbury attack.

The Foreign Secretary was urged to explain the answer he gave when asked why he was certain the novichok nerve agent originated in Russia.

On Tuesday, Britain's military research unit revealed to Sky News it was not yet able to establish where the substance used to poison Sergei and Yulia Skripal was made.

Gary Aitkenhead, chief executive of the Defence Science and Technology Laboratory (DSTL) at Porton Down, said scientists had not "identified the precise source".

"But," he added, "we have provided the scientific info to Government who have then used a number of other sources to piece together the conclusions you have come to".

It came two weeks after Mr Johnson gave an interview to the German broadcaster Deutsche Welle, and was asked why he believed the chemical came from Russia.

He said: "When I look at the evidence, I mean the people from Porton Down, the laboratory..."

Mr Johnson was asked if they had samples.

He said: "They do. And they were absolutely categorical and I asked the guy myself, I said, 'Are you sure?' And he said, 'There's no doubt'."

After Mr Aitkenhead's comments to Sky News, the Foreign Office released a statement saying it had been "clear from the very beginning" that Porton Down had identified the type of substance as novichok.

"This is only one part of the intelligence picture," a spokesperson said.

They cited Prime Minister Theresa May's announcement that Russia has for the last decade "investigated ways of delivering nerve agents probably for assassination".

The spokesperson added: "It is our assessment that Russia was responsible for this brazen and reckless act and, as the international community agrees, there is no other plausible explanation."

When asked for clarification on Mr Johnson's comments about Russia being the source, a Foreign Office source told Sky News he "misspoke", but that they could "see that" interpretation.

Responding, Labour MP Chris Williamson wrote on Twitter: "Dear Britain, Boris Johnson is your Foreign Secretary and he just lied to justify our country's foreign policy. How does that make you feel?"

And shadow home secretary Diane Abbott shared another post that said: "Listen, in his own words, to Boris Johnson claim he had categorical assurances from Porton Down that the nerve agent originated from Russia. This has today been exposed as incorrect."

Previously, Mrs May had cited Porton Down research to back up the Government's stance against Russia.

She said that "positive identification of this chemical agent by world-leading experts at the Defence Science and Technology Laboratory" was one of the pieces of evidence.

She also highlighted "knowledge that Russia has previously produced this agent and would still be capable of doing so, Russia's record of conducting state-sponsored assassinations and our assessment that Russia views some defectors as legitimate targets for assassinations". </s> Moscow's foreign minister Sergei Lavrov labelled the refusal "outrageous", adding that Britain was "putting all decency aside" as the countries expel each other's diplomats.

His comments came after Russia issued a failed request to the UK to visit Ms Skripal.

On Monday, chief executive Gary Aitkenhead said the deployment was "probably only within the capability of a state actor".

Experts at Porton Down, the UK defence laboratory, are still trying to establish how the agent was administered to ex-Russian spy Sergei Skripal and his daughter Yulia on March 4.

Defence experts still do not know the "precise source" of the Salisbury spy attack - but are "completely confident" the nerve agent used was novichok.

Speaking to ITV News, Mr Aitkenhead emphasised Porton Down's belief that novichok was the agent used.

But he stressed that it was the Government's conclusion that Russia was behind the attack.

Following Mr Aitkenhead's comments, a Government spokesman said: "We have been clear from the very beginning that our world-leading experts at Porton Down identified the substance used in Salisbury as a Novichok, a military grade nerve agent.

"This is only one part of the intelligence picture. As the Prime Minister has set out in a number of statements to the Commons since March 12, this includes our knowledge that within the last decade, Russia has investigated ways of delivering nerve agents probably for assassination - and as part of this programme has produced and stockpiled small quantities of Novichoks; Russia's record of conducting state-sponsored assassinations; and our assessment that Russia views former intelligence officers as targets.

"It is our assessment that Russia was responsible for this brazen and reckless act and, as the international community agrees, there is no other plausible explanation."

Scotland Yard has said that it is their belief the pair first came into contact with novichok at their home.

"Our job within the whole of this investigation is and was to identify the nerve agent used - which is from the family of novichok," Mr Aitkenhead said.

"We provided that information to the Government who have then used a number of other sources to come to the conclusions that they have."

He added: "I can only emphasise that our job within this whole episode is to provide scientific facts, evidence and input - which was identification of the agent - and that is what we have done." </s> Almost four ounces of Novichok nerve agent were used in the attack on former Russian spy Sergei Skripal and his daughter Yulia, the head of the Organisation for the Prohibition of Chemical Weapons (OPCW) has said.

Ahmet Uzumcu told the New York Times the amount of Novichok used - around half a cup of liquid - suggests it was created for use as a weapon rather than for research purposes.

Mr Skripal, 66, and his 33-year-old daughter Yulia were left fighting for their lives in hospital after being found unconscious on a park bench in Salisbury on March 4.

The inquiry into the nerve agent attack in the Wiltshire city has involved 250 detectives who have sifted through more than 5,000 hours of CCTV and interviewed more than 500 witnesses.

Mr Uzumcu told the newspaper the Novichok could have been applied as a liquid or aerosol.

He said: 'For research activities or protection you would need, for instance, five to 10 grams or so, but even in Salisbury it looks like they may have used more than that, without knowing the exact quantity, I am told it may be 50, 100 grams or so, which goes beyond research activities for protection.

'It's not affected by weather conditions. That explains, actually, that they were able to identify it after a considerable time lapse.'

He added the samples collected suggested the nerve agent was of 'high purity'.

Mr Skripal and his daughter have defied medical odds - he is no longer in a critical condition and she has been discharged from hospital.

Moscow has denied accusations it was responsible for the poisoning of the Skripals but the incident plunged diplomatic relations between Russia and the West into the deep freeze.

The Russian ambassador to the UK Alexander Yakovenko previously suggested that Sergei and Yulia Skripal may have been injected by British authorities with nerve agent produced at Porton Down.

However the UK has previously stated its conviction that only Russia had the means and motive to target the former spy.

Elsewhere today the Czech Republic's pro-Russian president Milos Zeman claimed a tiny amount of Novichok was produced, tested and destroyed in his country last year.

He cited a report by Czech military spies - but admitted that a separate report by a counterintelligence agency did not in fact identify the agent as Novichok, but as A230.

The 73-year-old, known for his pro-Kremlin views, said he thought it was the same nerve agent type used to poison ex-Russian spy Skripal and his daughter.

Moscow immediately jumped on the comments with a senator saying they were a 'crushing blow' to claims that Russia was behind the attack.

Russian officials have previously suggested the nerve agent used for the attack may have originated in the Czech Republic, Sweden and Slovakia.

Acting Czech Prime Minister Andrej Babis called that claim a lie and the Czechs expelled three Russian diplomats in solidarity with Britain.

Karen Pierce, the UK's representative to the United Nations, told a meeting last month there was 'no plausible alternative explanation than Russian State responsibility for what happened in Salisbury', suggesting Russia had the ability, operation experience and motive to carry out the attack.

She said: 'Russia has a proven record of conducting state-sponsored assassinations including on the territory of the United Kingdom.

'The independent inquiry into the death of Alexander Litvinenko concluded in January 2016 that he was deliberately poisoned with polonium; that the FSB had directed the operation; and that President Putin probably approved it.'

On the technical means of creating Novichok, she said: 'No terrorist group or non-state actor would be able to produce this agent in the purity described by the OPCW testing and this is something Russia has acknowledged.

'The Russian State has previously produced Novichoks and would still be capable of doing so today.' </s> Police officers stand guard outside of the home of former Russian military intelligence officer Sergei Skripal, in Salisbury, Britain, March 6, 2018. — Reuters picLONDON, April 4 — The British military facility analysing the nerve agent used to poison a spy said yesterday it could not prove the substance was made in Russia, as Russian President Vladimir Putin put his hopes in a meeting with the world’s chemical weapons watchdog.

Gary Aitkenhead, chief executive of the Porton Down defence laboratory, told Britain’s Sky News that analysts had identified the substance as military-grade Novichok, the word used for a category of nerve agents developed in Soviet times.

But he added: “We have not identified the precise source.”

“It is our job to provide the scientific evidence of what this particular nerve agent is, we identified that it is from this particular family and that it is a military grade, but it is not our job to say where it was manufactured,” Aitkenhead said.

He added that “extremely sophisticated methods” were needed to create the nerve agent, and that was “something only in the capabilities of a state actor”

Following his remarks, a British government spokesman said Porton Down’s identification of Novichok was “only one part of the intelligence picture”.

“This includes our knowledge that within the last decade, Russia has investigated ways of delivering nerve agents probably for assassination — and as part of this programme has produced and stockpiled small quantities of Novichok; Russia’s record of conducting state-sponsored assassinations; and our assessment that Russia views former intelligence officers as targets,” he added.

Former double agent Sergei Skripal, who has lived in Britain since a spy swap in 2010, and his daughter Yulia have been in hospital since March 4 after the poisoning that London and its major Western allies have blamed on Russia.

The first use of chemical weapons in Europe since World War II has chilled Moscow’s relations with the West, as both sides have expelled scores of diplomats.

Britain has also suspended high-level diplomatic contact with Moscow.

Moscow has denied any involvement in the incident, with Russian Foreign Minister Sergei Lavrov on Monday suggesting that the British government may be behind the poisoning to distract attention from problems around Brexit.

Aitkenhead would not comment on whether Porton Down had developed or keeps stocks of Novichok, but he dismissed claims the agent used to poison the Skripals had come from the site.

“There is no way anything like that could have come from us or left the four walls of our facility,” he said.

The Organisation for the Prohibition of Chemical Weapons (OPCW), the world’s chemical watchdog, will meet Wednesday to discuss Britain’s allegations that Russia was responsible for the poisoning, according to documents released yesterday.

The OPCW said Russia had asked for the meeting, which Putin said was aimed at putting an end to the ongoing dispute.

“We hope that during those discussions a full stop will be placed on (the issue of) what happened,” he said during a visit to the Turkish capital Ankara.

The meeting request came after Moscow received and analysed samples of the Novichok agent used in the attack.

The confidential gathering will start at 10:00 am (0800 GMT) at the OPCW’s headquarters in The Hague.

“We hope to discuss the whole matter and call on Britain to provide every possible element of evidence they might have in their hands,” Russia’s ambassador to Ireland, Yury Filatov, told reporters ahead of the OPCW meeting.

“Russia is interested in establishing the whole truth of the matter,” he said.

But Britain’s foreign ministry accused Russia of requesting the meeting to undermine the organisation’s investigation.

“This Russian initiative is yet again another diversionary tactic, intended to undermine the work of the OPCW in reaching a conclusion,” the ministry said in a statement.

“Of course, there is no requirement in the Chemical Weapons Convention for the victim of a chemical weapons attack to engage in a joint investigation with the likely perpetrator,” it said. — AFP
Military scientists at Porton Down state they are uncertain of the source of the nerve agent used, but are "completely confident" it was a Novichok agent.