Former MI6 spy Sergei Skripal and his daughter Yulia were poisoned using a novichok nerve agent, the international chemical weapons watchdog has confirmed.
Four separate laboratories around the world all reached the same conclusion as the UK government regarding the nature of the poison, the Organisation for the Prohibition of Chemical Weapons said in an executive summary of its findings.
The organisation was called in to carry out an independent investigation into the poisoning of the pair in Salisbury last month.
Its conclusion matches that of UK government scientists at the Porton Down defence laboratory and is likely to place fresh pressure on Russia to answer questions about its alleged involvement in the attack.
The Foreign Office claimed the finding proves there is ”no alternative explanation about who was responsible – only Russia has the means, motive and record” and demanded the Kremlin “give answers”.
While it did not name the specific chemical used, the OPCW said its scientists had “confirmed the findings of the United Kingdom relating to the identity of the toxic chemical”.
The UK government used its identification of novichok as a major strand of evidence in its decision to blame Russia for the attack. The “military grade” nerve agent is of a type known to have been manufactured by Russia and would likely have required state resources to produce, ministers said.
Russia has strongly denied any involvement in the attack, which initially left the Skripals in a critical condition in hospital. The condition of both victims has since improved, and Yulia Skripal was discharged from hospital earlier this week.
OPCW experts visited Salisbury last month and took blood samples from the Skripals and police officer Nick Bailey, who was also exposed to the toxin. Samples were also taken from sites known to have been contaminated by the nerve agent.
In the executive summary of its report, the OPCW said: “The results of analysis by the 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 that was used in Salisbury and severely injured three people.”
In a finding that appears to confirm suggestions the manufacturers of the novichok would have had significant expertise, the watchdog said the chemical was of “high purity” and noted an “almost complete absence of impurities”.
The full report is classified but will be sent to all OPCW member states, including Russia.
Boris Johnson, the foreign secretary, welcomed the finding.
“Today the international chemical weapons watchdog have confirmed the findings of the United Kingdom relating to the identity of the toxic chemical used in the attempted assassination of Mr Skripal and his daughter, and which also resulted in the hospitalisation of a British police officer,” he said. “That was a military grade nerve agent – a novichok.
“This is based on testing in four independent, highly reputable laboratories around the world. All 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 government had “never doubted the analysis of our scientists at Porton Down”, he added.
Mr Johnson said: “We will now work tirelessly with our partners to help stamp out the grotesque use of weapons of this kind and we have called a session of the OPCW Executive Council next Wednesday to discuss next steps. The Kremlin must give answers.
“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.”
Sergei and Yulia Skripal were discovered unconscious on a park bench in Salisbury on 4 March.
The former Russian army officer, who worked as a British spy, remains in hospital although his condition has improved from “critical” to “serious”.
The poisoning sparked a major diplomatic row between the UK and Russia after ministers blamed Moscow for the attack. Russia has said the UK has failed to provide any evidence as to who was behind the incident and warned Britain it was “playing with fire and will be sorry”.
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