Claiming that the substance used in the attack had been a Novichok-class nerve agent developed in the Soviet Union, London rushed to accuse Russian Federation of being involved in the incident.
The letter says the nerve agent used to poison the Skripals had most likely been made at a laboratory in Shikhany, near Volgograd, which is a branch of the State Institute for Organic Chemistry and Technology. The amateur, in his opinion, could not do this.
Testing by four laboratories affiliated with the global chemical weapons watchdog have confirmed British findings on the nerve agent used in March's attack on a former Russian spy in the United Kingdom, according to a summary of the findings published on Thursday.
But a Russian Foreign Ministry spokeswoman said the allegations were a "clear anti-Russian campaign, the like of which we have not seen in the world for a long time in terms of its scale and lack of principles". "This programme subsequently included investigation of ways of delivering nerve agents, including by application to door handles".
The Bishop of Salisbury, and the Rector of the parish in which nerve agent victims Sergei and Yulia Skripal were found, are welcoming all members of the public to a special "celebration" of the community life of the City.
The embassy believes that Sedwill's letter published on April 13 is "yet another confirmation there exists no proof of Russia's alleged involvement in the Salisbury incident". "It is highly likely that Novichoks were developed to prevent detection by the West and to circumvent worldwide chemical weapons controls", he said.
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Russian Federation blamed: The OPCW and Britain's Porton Down military research facility both said the Skripals were poisoned with a Novichok nerve agent, but neither could identify where it was manufactured.
"In 2017, we eliminated all chemical weapons", Yakovenko said.
"Only Russia has the means, motive and record", Johnson said.
Mr Skripal, 66, a former Russian spy who has British citizenship, is still being treated at Salisbury District Hospital. "We have information indicating Russian intelligence service interest in the Skripals, dating back at least as far as 2013, when email accounts belonging to Yulia Skripal were targeted by GRU (military intelligence) cyber specialists".
No sooner had the Organization for the Prohibition of Chemical Weapons (OPCW) announced its findings in the Skripal poisoning case; Russian media launched a veritable avalanche of fakes in the matter.
The Russian embassy, which has repeatedly demanded access to the Skripals, cast doubt on the authenticity of her statement Thursday. "We didn't produce Novichok, we didn't store this Novichok, so-called under the Western classification", he said.