In a declassified summary of its findings, however, the OPCW did not make any assessment on who carried out the March 4 attack on 66-year-old former double agent Sergei and his daughter Yulia in the English city of Salisbury that also injured a police officer.
He said the watchdog's findings were based on testing in four independent, highly reputable laboratories around the world, all of which returned the same "conclusive" results.
"There can be no doubt what was used and there remains no alternative explanation about who was responsible only Russia has the means, motive and record The Kremlin must give answers," he added.
The minister said the UK had asked the OPCW to publish the executive summary of its findings in the "interest of transparency" and called a session of the OPCW Executive Council next Wednesday to discuss next steps.
"We must, as a world community, stand up for the rules based order which keeps us all safe. The use of weapons of this kind can never be justified, and must be ended," Johnson said.
The UK's finding of a Soviet era Novichok stock of nerve agent used in the attack against the Skripals had been presented before the House of Commons by British Prime Minister Theresa May last month, when she declared that Russia was "culpable".
The UK government has since made several statements pointing the finger of blame of the Kremlin and expelled Russian diplomats in retaliation of the poisoning of the Skripals. The incident has led to a diplomatic crisis between Moscow and the West as Moscow denies any involvement and accuses Britain of inventing a "fake story".
In retaliation, Russia also expelled 60 American diplomats.
The OPCW report comes as Yulia turned down help from the Russian embassy in a statement issued through Scotland Yard on Wednesday to say that she was "safe" and trying to come to terms with her new life.
"I find myself in a totally different life than the ordinary one I left just over a month ago, and I am seeking to come to terms with my prospects, whilst also recovering from this attack on me," she said.
The 33-year-old Russian citizen has been taken to a secure location after being discharged from Salisbury District Hospital earlier this week. In her statement, she said that she has been made aware of the Russian embassy's attempts to contact her but she did not wish to avail of their services for the moment.
"I have access to friends and family, and I have been made aware of my specific contacts at the Russian Embassy who have kindly offered me their assistance in any way they can. At the moment I do not wish to avail myself of their services, but, if I change my mind I know how to contact them," she said in her statement through the Metropolitan Police.
"Most importantly, I am safe and feeling better as time goes by, but I am not yet strong enough to give a full interview to the media, as I one day hope to do. Until that time, I want to stress that no one speaks for me, or for my father, but ourselves, she added.
Making a specific reference to her Russia-based cousin, Viktoria, she said that "her opinions and assertions are not mine and they are not my father's".
Viktoria had been quoted widely in the Russian media following a phone conversation she claimed to have had with Yulia from hospital last week.
The Russian embassy in London immediately raised doubts over the authenticity of the statement, claiming it "only strengthens suspicions that we are dealing with a forcible isolation of the Russian citizen".
"With no possibility to verify it, the publication by the Metropolitan Police raises new questions rather than gives answers. As before, we would like to make sure that the statement really belongs to Yulia. So far, we doubt it much," an embassy statement said.
Sergei Skripal remains in hospital as he recovers from the effects of the toxic nerve agent. His daughter thanked the Salisbury hospital staff, adding: "I have left my father in their care, and he is still seriously ill. I too am still suffering with the effects of the nerve agent used against us."
The UK's intelligence officials are believed to be in talks with the CIA over the possible repatriation of the Skripals to the US or another friendly country for their safety.
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