It also received parts of samples taken by the British authorities which were analysed in OPCW-designated laboratories for "comparative purposes".
The U.K. has said its experts from the Porton Down defense research center concluded that the military-grade nerve agent that was used in the attack belonged to a Russia-developed chemical weapon group called Novichok.
"Mr. Skripal and his daughter were poisoned with a military-grade nerve agent of a type developed by Russian Federation", specifically from the Novichok group, British Prime Minister Theresa May said following an immediate assessment by British experts.
According to the embassy's maycommentary, "the case against Russian Federation is based on three elements: the identification of the chemical agent, far-fetched speculations and conclusions regarding the "operational experience" and "motive", as well as unverifiable 'intelligence'".
The Organisation for the Prohibition of Chemical Weapons (OPCW) said its inspectors had found the toxin used was of "high purity" with an "almost complete absence of impurities". The analyses - carried out on blood of poisoned and remains at scene - have been carried out by four independent laboratories of OPCW, although affiliated with organization based in The Hague, reports Reuters.
Although Yulia has to undergo further treatment, doctors treating the Ms Skripal have said they were more than happy to discharge her after she made a remarkable recovery in such a short space of time.
The Russian embassy, which has repeatedly demanded access to the Skripals, cast doubt on the authenticity of her statement Thursday.
She said she had been made aware of the Russian embassy's attempts to contact and offer her assistance by "at the moment I do not wish to avail myself of their services". Alexander Yakovenko told reporters.
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".
Salisbury District Hospital said Sergei Skripal was still in the hospital but showing progress. It insists that the nerve agent used on the Skripals could easily have been manufactured in any of the other countries that have advanced chemical research programs.
Sergei Skripal remains seriously ill in hospital.
The UK's intelligence officials are believed to be in talks with the CIA over the possible repatriation of the Skripals to the United States or another friendly country for their safety.