This Nov. 15, 2013, photo shows an exterior view of the Organization for the Prohibition of Chemical Weapons (OPCW) building in The Hague. (Lex Van Lieshout/AFP/Getty Images)

The international watchdog agency that monitors the use of chemical weapons said Thursday that its independent investigators have confirmed Britain’s assertions that the toxic chemical used to poison former Russian double agent Sergei Skripal and his daughter was a military-grade nerve agent known as Novichok. 

The Organization for the Prohibition of Chemical Weapons (OPCW) sent a team of investigators to Britain, where they took blood samples from Yulia and Sergei Skripal and Salisbury police officer and first responder Nicholas Bailey. During its stay from March 21 to 23, the OPCW team also took samples of the nerve agent from Salisbury.

In a report published Thursday, the OPCW said it confirmed “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 separate, classified report, the OPCW investigators described the formula and signature of the nerve agent used in precise detail. They did not include the formula in the public report, in part because they do not want anyone else to try to replicate the agent.

The OPCW also did not say who had manufactured the nerve agent or where or when it was created. But the report noted that it was of “high purity” with “the almost complete absence of impurities.” 

British officials, speaking on the condition of anonymity to discuss the case, said the high purity of the chemical points toward its creation in a sophisticated, government-run laboratory — and not some terrorist’s kitchen.

British Foreign Secretary Boris Johnson said in a statement: “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.”

Britain said Russia — in violation of chemical weapons treaties — has produced the Novichok class of nerve agents in the past 10 years. 

Russia has denied any wrongdoing in the case. Instead, its top diplomats have charged that Britain either rushed or bungled its investigation, or that British agents were responsible for the poisoning — to justify increased military spending, smear Russia or distract citizens from stumbling Brexit negotiations.

The report comes a day after Yulia Skripal, 33, said she now has a “a totally different life than the ordinary one I left just over a month ago.” She was recently discharged from Salisbury District Hospital, where she said her father remains “seriously ill.”

Yulia and Sergei Skripal, a former Russian double agent, were found on March 4 slumped over on a park bench in Salisbury, a quiet city in the southwest of England.

In a statement issued via police, she rejected assistance from the Russian Embassy “at the moment.” Yulia Skripal is a Russian citizen who was in England to visit her father.

A few hours before the release of the OPCW report, the director of Britain’s surveillance agency, Jeremy Fleming, accused Russia of being “reckless” in mounting a nerve-agent attack on British soil.

Fleming blamed “the Kremlin” for the poisoning. The surveillance agency — the Government Communications Headquarters, or GCHQ — plays a role similar to that of the National Security Agency in the United States.

Speaking at a cybersecurity conference in Manchester, Fleming said the attack in Salisbury “demonstrates how reckless Russia is prepared to be, how little the Kremlin cares of the rules-based order, how comfortable they are at putting ordinary lives at risk.”

Fleming said Britain was prepared to respond to assaults by carrying out its own cyberattacks.

“We must not and have not forgotten the old foes,” he said. “For decades, we have collected intelligence on Russian state capabilities, on their intent and posture. And for over 20 years, we’ve monitored and countered the growing cyberthreat they pose to the U.K. and our allies. This has never gone away.”

Fleming called the Salisbury attack “stark and shocking.”

He said, “I’ll repeat, the attack on Sergei and Yulia Skripal in Salisbury was the first time a nerve agent had been deployed in Europe since the Second World War. That’s sobering.”