Repeated accusations: Russian Federation has repeatedly thrown out accusations of conspiracy in the poisoning of the Skripals.
In a letter to the head of Nato, Sir Mark Sedwill also said that Moscow had an assassination programme based around nerve agents that included attacking a victim by smearing poison on a door handle.
Britain named it as Novichok, a group of powerful and deadly chemical compounds developed by the Soviet government in the 1970s and 1980s.
But Mr Sedwill's letter suggested the nerve agent used was most likely to have been made at a laboratory in Shikhany, near Volgograd, a branch of the State Institute for Organic Chemistry and Technology.
"It is highly likely that Novichoks were developed to prevent detection by the West and to circumvent global chemical weapons controls", Sir Mark wrote. "Within the last decade, Russian Federation has produced and stockpiled small quantities of Novichoks". "The use of weapons of this kind can never be justified, and must be ended", he said.
The Organization for the Prohibition of Chemical Weapons (OPCW) sent a team to Britain from March 21 to March 23 where they took blood samples from Yulia and Sergie Skripal and the Salisbury police officer and first responder Nicholas Bailey.
The BBC's diplomatic correspondent James Landale said: "This is understood to strengthen the argument that this substance came from Russian Federation because it is more likely to have been created by a state actor with the capability to make the nerve agent". In a diplomatic row that followed a number of Western countries "in a gesture of solidarity" with Britain expelled Russian diplomats.
In announcement made on Tuesday, the Medial Director of Salisbury General Hospital Dr Christine Blanshard, confirmed that the 33 year old daughter of former Russian agent Sergei Skripal, was released in good health.
"Only Russia has the means, motive and record", Johnson said.
"There is no plausible alternative explanation". Moscow rejected all of the United Kingdom's accusations, saying that a program aimed at developing such a substance had existed neither in the Soviet Union nor in Russian Federation.
He went on: "We didn't produce and store Novichok, so this is the fact of life and all these allegations that we produce something have nothing to do with the reality".
Russian Federation had stopped its chemical programs in 1992 and eliminated all chemical weapons in 2017, he said. Russia's ambassador to Britain, Alexander Yakovenko, identified the poison as Novichok A-234, derived from an earlier version known as A-232.
"There are over 100 British journalists here, why are none of you calling to meet Miss Skripal - not a single person?" Yulia has been discharged and is reportedly being kept at an MI5 "safe house".
She also said she would give interviews to the media in time, but asked the press to have patience while she recovers.