Jeremy Corbyn has denied allegations that he met with a Soviet spy and supplied information to the communist regime in exchange for money during the Eighties.
Czech diplomat Jan Sarkocy, who was a communist spy during the Cold War, has said that the Islington MP, using the name Agent Cob, met with him in parliament and warned him about British operations against communist agents in 1987.
Corbyn allegedly told the Soviet agent, who was expelled from the UK by Margaret Thatcher's government, that MI5 was investigating suspected communist spies.
Sarkocy claims that the Labour leader handed him a newspaper cutting warning about the British operation.
The pair also met on two other occasions, at the House of Commons in 1986 and at the politician's constituency office in Islington the following year, secret documents obtained by The Sun revealed.
On Friday (16 February), Sarkocy said that Corbyn was fully aware that he was an agent, not a diplomat, when they met in the 1980s.
"Everybody knew that 'diplomat' was just a cover for spy," he told Czech media. "It was a conscious cooperation. Diplomat and agent were the same thing."
"He also received money," Sarkocy said, claiming that he gave Corbyn cash in exchange for information. He said Corbyn's information was "rated in Moscow as the number one."
"Mr Corbyn was an honest man, but stupid," he added.
A spokesperson for the Labour leader has dismissed the allegations as a "ridiculous smear and entirely false."
"As Svetlana Ptacnikova, director of the Czech Security Forces Archive, has made clear, Jeremy was neither an agent, asset, informer nor collaborator with Czechoslovak intelligence," he said.
"The former Czechoslovak agent Jan Sarkocy's account of his meeting with Jeremy was false 30 years ago, is false now and has no credibility whatsoever," the spokesman added. "His story has more plot holes in it than a bad James Bond movie."
Ptacnikova confirmed that the pair had met, but said that Corbyn was "neither registered as a collaborator, nor does this [his alleged collaboration] stem from archive documents."