A British couple who both fell ill on Saturday after visiting Salisbury, the English town where a former Russian double agent and his daughter were poisoned in March, were exposed to Novichok, the same military-grade nerve agent used in that attack, Britain’s top counterterrorism official said on Wednesday.

Metropolitan Police Assistant Commissioner Neil Basu told reporters that tests carried out by chemical weapons experts at Porton Down, the British military lab near Salisbury, “confirm that the man and woman have been exposed to the nerve agent Novichok, which has been identified as the same nerve agent that contaminated both Yulia and Sergei Skripal.”

The couple, identified by the British media as Dawn Sturgess and Charlie Rowley, were hospitalized on Saturday and are currently in critical condition in Salisbury District Hospital, where the Skripals were treated after an apparent assassination attempt in March.

Although Basu said the poison was Novichok, one of a series of chemical weapons developed by Russia, “we are not in a position to say whether the nerve agent was from the same batch that the Skripals were exposed to.”

Speaking to Parliament on Thursday, Britain’s home secretary, Sajid Javid, connected the new episode to what he called the “reckless” decision “taken by the Russian government” to deploy a chemical weapon in Salisbury in March. “It is now time,” Javid added, “that the Russian state comes forward and explains exactly what has gone on.”

Russia’s foreign ministry spokesperson, Maria Zakharova, responded by accusing British Prime Minister Theresa May of “intrigue and games with chemically poisonous substances.”

Since the poisoning of the Skripals, Russian officials have promoted a variety of conspiracy theories suggesting that the attack was staged by British intelligence to discredit the Kremlin.

The new victims live in the town of Amesbury, but reportedly visited Queen Elizabeth Gardens in Salisbury last week. That park, which is only eight miles from the couple’s home, is one of five sites now cordoned off by the police.

Investigators are currently trying to determine if Sturgess and Rowley might have accidentally come into contact with residue of the nerve agent left behind by the Skripal attackers, Ben Wallace, Britain’s minister of state for security, told Deborah Haynes, the Times of London defense editor.

Russian diplomats entered the social media discussion of the incident by mocking the idea that the Russia was to blame for the attempted assassination of the Skripals and promoting a conspiracy theory based on the proximity of the poisonings to Britain’s own chemical weapons lab at Porton Down.

Dan Kaszeta, a chemical weapons expert based in London, noted that the class of Russian nerve agents known as Novichoks were designed during the Cold War to outlast defensive measures taken by enemy soldiers.

Mark Urban, the diplomatic editor of the BBC program “Newsnight,” reported on Wednesday that Britain told NATO allies in March that it had intelligence showing that Russia had been keeping the Skripal family under surveillance and that Russian military intelligence had hacked into Yulia Skripal’s email accounts.

The poisoning of two British citizens by a Russian-developed nerve agent, even if accidental, comes at an awkward moment, as Russia tries to rehabilitate its international image. The news broke as Russia was earning plaudits for hosting a successful World Cup tournament, in which its national team has so exceeded expectations that it could even reach the semifinals next week, where one of two possible opponents is England.

That match is scheduled for Wednesday, the same day that Donald Trump arrives in Europe for a NATO meeting, a visit to Britain, and a summit with President Vladimir Putin. In advance of his meeting with Putin, Trump has repeatedly insisted that there is no longer any reason to isolate Russia, since its interference in the affairs of other nations “happened a while ago” and is now a thing of the past.

Update: July 5, 2018, 9:22 a.m. EDT
This report was revised to add more information about the poisoning of a British couple who visited the town of Salisbury recently, and reaction from British and Russian officials.

Top photo: Metropolitan Police Assistant Commissioner Neil Basu and Dame Sally Davies, chief medical officer for England, updated reporters at New Scotland Yard in London on Wednesday on a British couple who were hospitalized after exposure to a military-grade nerve agent of a type developed in Russia.