The lethal poison that struck down a former Russian spy and his daughter last month in England was a highly pure type of Novichok nerve agent, the global chemical weapons watchdog has concluded, backing Britain's findings.
Sergei Skripal, a former colonel in Russian military intelligence and his daughter Yulia were found unconscious on a bench in the English city of Salisbury on March 4.
Britain blamed Russia for the poisoning and Prime Minister Theresa May said that the Skripals had been attacked with a military-grade nerve agent from the Novichok group of poisons, developed by the Soviet Union in the 1970s and 80s.
- Nerve agent attack 'somewhat disorientating' - victim
- Russian media goes into overdrive denying involvement
Moscow denied any involvement and suggested Britain had 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.
Testing by four laboratories affiliated with the global chemical weapons watchdog has now confirmed Britain's findings and showed that the toxic chemical was "of high purity".
The OPCW did not explicitly name Novichok in its published summary, say where the poison may have come from or assign blame for the attack. But it did confirm Britain's analysis about the substance that had been used.
"The results of analysis by OPCW-designated laboratories of environmental and biomedical samples collected by the OPCW team confirm the findings of the United Kingdom relating to the identity of the toxic chemical," the published summary said.
British Foreign Secretary Boris Johnson said on Thursday the findings show "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".
Responding to the summary, Moscow said that it had reason to think the report was part of a British operation to discredit Russia. Foreign Ministry spokeswoman Maria Zakharova said Moscow would not believe any conclusions about the poisoning unless Russian experts were given access to the investigation.
And Georgy Kalamanov, Russia's deputy minister of industry and trade, told the Interfax news agency that it was impossible to pinpoint the agent's origin and reiterated Moscow's demand for a fresh investigation with Russian involvement.
German Foreign Ministry spokesman Juergen Hardt said the OPCW confirmed Britain's analysis. "It is now up to Russia to finally play a constructive role and answer the open questions," 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 Russia is prepared to be", the head of Britain's GCHQ spy agency said on Thursday.
Yulia Skripal, who was released from hospital on Monday, said in a statement she was still suffering effects of the poisoning and her father remained seriously ill. She said she had declined an offer of assistance from the Russian Embassy.
Ms Zakharova also challenged Britain to prove the Skripals were not being held hostage, noting that no one except British authorities had seen either of them for over a month.