"There can be no doubt what was used and there remains no alternative explanation about who was responsible - only Russian Federation has the means, motive and record", British Foreign Secretary Boris Johnson said in a statement celebrating the OPCW report.
The OPCW did not publically name the chemical, though it said it had identified it and its chemical structure in its secret report.
Britain said that Russian Federation - in violation of chemical weapons treaties - has produced the Novichok class of nerve agents in the last 10 years.
British Foreign Secretary Boris Johnson said there was "no alternative explanation" when it came to culpability for the apparent attack on the father and daughter on March 4 in the British cathedral city of Salisbury, where they were found slumped comatose on a public bench.
"There remains no alternative explanation about who was responsible - only Russian Federation has the means, motive and record", he said. Britain has blamed Russian Federation for the attempted murder - a charge that Moscow has strongly denied.
Russian Federation denies the British claims about Novichok, saying that it completed the destruction of all its Soviet-era chemical weapons arsenals previous year under global oversight.
"If someone was spying, why were the British services not complaining about that?"
"It is highly likely that Novichoks were developed to prevent detection by the West and to circumvent global chemical weapons controls", he said.
The statement comes two days after she was released from Salisbury District Hospital.
The testimony of the Skripals will be crucial in establishing the credibility of the British government's claim that it was "highly likely" that the Russian state had targeted them with the nerve agent.
She also thanked Viktoria Skripal for her concern but asked her cousin not to "visit me or try to contact me for the time being". Alexander Yakovenko told reporters.
The claims are made in a letter from Sir Mark Sedwill, the UK's national security adviser, to the North Atlantic Treaty Organisation secretary general, Jens Stoltenberg. Her father remains hospitalized but British health officials say he is improving.
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".