Kremlin critic Alexei Navalny said on Monday he had tricked a Russian secret agent into disclosing details of the botched plot to kill him and had been told that poison had been placed in his underpants.
Navalny, one of President Vladimir Putin's most outspoken critics, was airlifted to Germany for treatment in August after collapsing on a plane in Russia. Germany has said he was poisoned with a Soviet-style Novichok nerve agent in an attempt to murder him, an assertion many Western nations accept.
Navalny declared his poisoning case solved earlier this month when a joint media inquiry said it had identified a team of assassins from Russia's FSB security service.
In a video published on his website on Monday, Navalny said he had phoned up some of his alleged poisoners before the joint investigation was released and posed as an aide to the secretary of Russia's Security Council.
One of the men, named by Navalny as an employee of Russia's FSB security service, spoke to him for 49 minutes and appears to have been part of the clean-up team, he said. Navalny published a recording and transcript of the conversation.
Reuters could not independently verify the fact of the phone call or the identity of Navalny's interlocutor.
The Kremlin has repeatedly rejected any suggestion that Russia tried to kill Navalny.
"The video clip with the phone call is fake," the FSB said, according to the state TASS news agency, calling Navalny's investigation into his alleged poisoning a "planned provocation".
In the video, Navalny can be heard asking a voice on the phone. "Why did nothing work out?"
"Well, I've asked myself this question more than once," the voice responds.
When asked why Navalny survived, the voice says it was probably because the plane he was on at the time made an unplanned emergency landing and he was treated professionally and quickly by Russian medics.
"If it had been a bit longer, then it's possible it would all ... have ended differently," the voice says.
Putin last week dismissed media reports about Navalny's poisoning, saying they were made up of information provided by U.S. intelligence services and were an attempt to smear Putin himself and make Navalny seem more important than he really was.
Navalny is convalescing in Germany, but has said he plans to return to Russia at an undisclosed date.
