Russia's envoy at the global chemical weapons watchdog says Britain and the USA both have access to the nerve agent used in the poisoning of the ex-spy in Britain.
London, Mar 18 Britain's foreign secretary said Sunday that the trail of blame for the poisoning of a former spy "leads inexorably to the Kremlin", after a Russian envoy suggested the nerve agent involved could have come from a United Kingdom lab.
London has responded with a refusal to a note by the Russian Foreign Ministry requesting access to ex-GRU Colonel Sergei Skripal poisoned in Salisbury.
Mr Chizhov told the BBC's Andrew Marr show that Mr Skripal could "rightly be referred to as a traitor".
He added: 'I exclude the possibility of any stockpiles of any chemical weapons fleeing Russian Federation 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 Russian Federation and are now residing in the United Kingdom'.
UK-Russian relations have seriously deteriorated over the Salisbury incident where former Russian intelligence officer Sergei Skripal and his daughter were found unconscious in a shopping center.
The source of the nerve agent - which Britain says is Soviet-made Novichok - is unclear, as is the way it was administered. They remain in critical condition.
Russia's ambassador to the EU, Vladimir Chizhov, prompted a strong rebuttal when he suggested the poison may have come from the Porton Down laboratory, which is around eight miles from Salisbury.More news: Thousand Oaks California shooter: Mall evacuated amid reports of 'two down'
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Johnson said it was "not the response of a country that really believed itself to be innocent".
Britain and Russian Federation have each expelled 23 diplomats and taken other measures in the escalating tit-for-tat dispute.
While Russia has vigorously denied involvement in the attack, Western powers see it as the latest sign of alleged Russian meddling overseas. President Vladimir Putin is widely expected to win a fourth term.
It warned London it stood ready to take further measures in the event of more "unfriendly steps".
"I will announce in the coming days the measures that we intend to take", Macron said.
Britain, the US, Germany and France have jointly called on Russia to explain the attack, while US President Donald Trump has said it looks as if the Russians were behind it.
Writing in the Sun on Sunday two weeks after the March 4 incident, Mr Johnson said of Saturday's expulsions: "These futile measures will only punish ordinary Russians by depriving them of harmless opportunities to learn English and apply for United Kingdom visas". Meanwhile, Russia's ambassador in London, Alexander Yakovenko, called for "cooler heads".
But Russian presidential contender Ksenia Sobchak, a former TV star who is the only candidate to openly criticize Putin, said blame did not lie entirely with Britain.