The Czechoslovak secret agent who met Jeremy Corbyn during the Eighties claimed last night that the Labour leader knew he was a spy and said the MP had supplied information to the Communist regime.

Speaking for the first time since it emerged that he had met Mr Corbyn, Jan Sarkocy on Friday dismissed the suggestion that the Islington North MP believed he was simply a diplomat.

“Everybody knew that ‘diplomat’ was just a cover for spy,” he said. “It was a conscious cooperation. Diplomat and agent were the same thing.”

Mr Corbyn has denied being an agent or informer, but Mr Sarkocy, who was expelled from the UK by Margaret Thatcher and now lives in Bratislava, said that the information revealed by the MP – whose codename was Agent Cob – was “rated in Moscow as the number one”.

He also said that more meetings - in addition to the three disclosed earlier this week - took place between the pair.

Mr Sarkocy said it was routine for the Czechoslovak secret services to pay informants, but he stressed he had not personally handed over any money to Mr Corbyn.

“Mr Corbyn was an honest man, but stupid,” he said.