A Russian official has suggested the nerve agent used in the Salisbury spy poisoning could have come from a research laboratory in the UK.
Russia’s EU ambassador claimed Russia had 'nothing to do' with former Russian spy Sergei Skripal and his daughter Yulia being poisoned with “military grade” Novichok nerve agent in the Wiltshire city.
Vladimir Chizhov told the BBC's Andrew Marr Show Russia did not stockpile the poison and that the Porton Down lab - Britain's military research base - was only eight miles from the cathedral city, insinuating that may have been the source.
However the government has rebuffed his comments as “nonsense” - the Foreign Office said there was 'not an ounce of truth' in his implication the nerve agent could have been linked to Porton Down.
'It's just another futile attempt from the Russian state to divert the story away from the facts - that Russia has acted in flagrant breach of its international obligations,” a spokesperson said.
Theresa May told MPs Porton Down identified the substance used on Mr Scribal and his daughter - who remain in a critical but stable condition - as being part of a group of military grade nerve agents known as Novichok developed by Russia.
Earlier in the week, UK defence secretary Gavin Williamson pledged an additional £48m for a new chemical warfare defence centre at Porton Down in the wake of the poisoning.
Mr Chizhov said Mr Skripal could 'rightly be referred to as a traitor' but 'from the legal point of view the Russian state had nothing against him”.
Asked how the nerve agent came to be used in Salisbury, he said: 'When you have a nerve agent or whatever, you check it against certain samples that you retain in your laboratories.
'And Porton Down, as we now all know, is the largest military facility in the United Kingdom that has been dealing with chemical weapons research. And it's actually only eight miles from Salisbury.'
Pobed about whether he was signalling Porton Down was 'responsible' for the Novichok toxin employed in the attack, Mr Chizhov said: 'I don't know. I don't have any evidence of anything having been used.'
He added: 'I exclude the possibility of any stockpiles of any chemical weapons fleeing Russia after the collapse of the Soviet Union, but there were certain specialists, including some scientists who today claim to be responsible for creating some nerve agents, that have been whisked out of Russia and are currently residing in the United Kingdom.'
Mr Chizhov's remarks come in the wake of a Russian foreign ministry spokeswoman saying the UK was one of the most likely sources of the nerve agent, along with Slovakia, Czech Republic, Sweden or possibly America.
Maria Zakharova said a large number of ex-Soviet scientists had relocated to the West - 'taking with them the technologies that they were working on'.
On Saturday, Russia ordered 23 British diplomats to leave Moscow within a week in response to Britain's decision to expel 23 Russian diplomats amid an escalating row between the two countries over the nerve agent attack.
Russia has also said it will close the British Council in Russia - which promotes cultural links between the countries - and the British Consulate in St Petersburg.
Foreign Secretary Boris Johnson has said Britain possesses evidence Russia has been exploring nerve agent based assassinations and that the country has been stockpiling deadly chemical weapons in the last decade.
Mr Johnson specifically claimed Britain has reason to believe Moscow has been collecting novichok.
'We actually have evidence within the last ten years that Russia has not only been investigating the delivery of nerve agents for the purposes of assassination, but has also been creating, stockpiling, Novichok,' Mr Johnson told the Andrew Marr show on Sunday.
This comes after Mr Johnson said it was 'overwhelmingly likely' Russian president Vladimir Putin directed the use of the nerve agent on Britain's streets.
Speaking during a visit to the Battle of Britain Bunker museum in Uxbridge alongside the Polish foreign minister, Jacek Czaputowicz, Mr Johnson said: 'Our quarrel is with Putin's Kremlin, and with his decision - and we think it overwhelmingly likely that it was his decision - to direct the use of a nerve agent on the streets of the UK, on the streets of Europe, for the first time since the Second World War.”
Mr Johnson's move to publicly blame Mr Putin was understood to have been an intentional choice rather than an off-the-cuff gaffe. It is believed Mr Johnson may have seen information which enabled the government to reach that conclusion.
However, the Russian government has denied any involvement in the attack. The Foreign Secretary's comments were rebuked by Mr Putin's spokesman Dmitry Peskov, who said: 'We have said on different levels and occasions that Russia has nothing to do with this story. Any reference or mentioning of our president is nothing else but shocking and unpardonable diplomatic misconduct.