Skripal moved to Britain in a spy swap in 2010 and settled in Salisbury, and his daughter Yulia was visiting from Russian Federation when they were poisoned, possibly on his front door.
Britain blames Russian Federation for the March 4 poisoning of Sergei Skripal and his daughter, Yulia, with a nerve agent developed by the Soviet Union.
Moscow has suggested Britain carried out the attack to stoke anti-Russian hysteria, but Britain asked the Organisation for the Prohibition of Chemical Weapons (OPCW) to check samples from Salisbury.
Mr Johnson said the United Kingdom had invited the OPCW to test the samples "to ensure strict adherence to global chemical weapons protocols". It did not assign blame or give suggestions of the toxin's origin.
But it did confirm Britain's analysis about the substance that had been used.
British officials, speaking on condition of anonymity to discuss the case, said that the high purity of the chemical points toward its creation in a sophisticated laboratory.
Moscow strongly denies involvement in the attack, which has sparked an worldwide row resulting in the expulsions of diplomats from all sides.
However Russia, which has denied it played any role in the attack on the Skripals, said it believed the watchdog's report was part of a British operation to discredit Russia. Russian Federation denies this and says the nerve agent used on the Skripals could easily have been manufactured in another country.
British Foreign Secretary Boris Johnson hailed the findings. But British Foreign Minister Boris Johnson said only Russian Federation had the "means, motive, and record" to carry out such an attack.
German Foreign Minister Heiko Maas urged Russian Federation to answer "open questions" regarding the report and welcomed Britain's call for a special OPCW executive council session next week.
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Members of the Arizona National Guard listen to instructions on April 9, 2018, at the Papago Park Military Reservation in Phoenix. Jerry Brown, a Democrat, has not yet said how - or if - his state will comply with Trump's request for troops to the border.
"The UK has called for a UNSC meeting on the OPCW report on the Salisbury incident".
"This finding massively increases the pressure on Moscow to fully explain the exact course of events and background of the first nerve agent attack on European soil", he said.
The poisoning of Mr Skripal, who settled in Britain in 2010 after being released by Moscow in a spy swap, shows "how reckless Russian Federation is prepared to be", the head of Britain's GCHQ spy agency said on Thursday.
She said her father "is still seriously ill" and said she herself is "still suffering with the effects of the nerve agent used against us".
In a statement Wednesday, Yulia Skripal said she did not need help from Russian diplomats in the United Kingdom and cautioned the media that no one else speaks for her or her father, who is still in a British hospital.
Russian Foreign Ministry information and press director Maria Zakharova said the allegations in relation to the poisoning of Sergei and Yulia Skripal 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 has also prevented it from acting on the use of chemical weapons in Syria. Russia's ambassador to Britain, Alexander Yakovenko, identified the poison as Novichok A-234, derived from an earlier version known as A-232.
The report does not name the source of the nerve agent, a subject which is beyond the remit of the inspectors.
It noted that the chemical was of "high purity" with an "almost complete absence" of any impurities.
The laboratory results, which came in on Wednesday night, were to be circulated to OPCW member states on Thursday.