After more than two months, 66-year-old former Russian spy Sergei Skripal has been discharged from the hospital after being poisoned by a military-grade nerve agent, British authorities said Friday.

The former Russian double agent and his daughter, Yulia Skripal, were attacked in the southern English city of Salisbury on March 4 and found slumped over on a park bench.

Last month, British officials said for the first time that Skripal was no longer in critical condition, having joined his daughter in a recovery that could lead to the pair helping investigators uncover what happened March 4. Skripal was still being questioned by investigators as recently as this week, according to British media reports.

“It is fantastic news that Sergei Skripal is well enough to leave Salisbury District Hospital,” Cara Charles-Barks, the hospital’s chief executive, said in a statement Friday. The hospital did not release a detailed assessment of the Skripals’ recovery, citing the two patients’ right to privacy.

Malcolm Sperrin, a medical physicist, cautioned in April that a long-term prognosis for the Skripals remained somewhat uncertain. Referring to Yulia, he said: “She might talk and converse, but what we don’t know is if she will go back to where she was before the event, not just about cognition, but there’s other aspects that could be affected, like mobility, problems with mental state, anxiety, depression. There are so many unknowns.”

British Prime Minister Theresa May condemned the poisoning as a reckless and hostile act by Russia on British soil. May subsequently decided to expel 23 Russian diplomats from Britain in the biggest such move since 1985, years before the end of the Cold War. At least 26 other countries, including many European Union member states, the United States and Australia, joined the retaliatory measures after May provided confidential evidence about Russia’s alleged involvement. The documents have not been made public.

May and her government say that in addition to the forensic evidence shared with allies, Russia is also suspected because it has assassinated critics abroad before.

In 1992, two Russian scientists approached The Post’s Will Englund, then the Moscow correspondent for the Baltimore Sun, with news of a secret nerve agent. (Joyce Lee, Will Englund/The Washington Post)

Skripal was a double agent who sold secrets to Britain. He was convicted and jailed in Russia but released in a swap of intelligence agents in 2010.

Britain’s Foreign Ministry said in a statement in April, “Let us be clear, this was attempted murder using an illegal chemical weapon that we know Russia possesses.”

But Russia has denied having anything to do with the attack. Top Russian diplomats have insisted that Britain either rushed or bungled the investigation — or that British agents themselves may have poisoned the father and daughter to smear Russia, justify increases in military spending or distract residents from the failures of Brexit negotiations.

British authorities have refused to discuss the “security arrangements” in place after the Skripals’ discharge, and they are shielding the two former patients from the public. Dismayed by Britain’s secrecy, the Russian government has repeatedly criticized London’s reluctance to provide Russian diplomats access to the Skripals.

“Under the current conditions, we are forced to qualify this situation as forcible detention and even the abduction of our two citizens by the British authorities,” Russian Foreign Ministry spokeswoman Maria Zakharova said during a news briefing on Wednesday.

William Booth and Karla Adam in London contributed to this report.

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