Jeremy Corbyn  has flatly denied that he was a spy for communist Czechoslovakia during the Cold War.

The Labour leader dismissed the claims, which originally appeared in The Sun, that he passed information to an agent of the Czech StB intelligence agency during the 1980s as “nonsense”.

Mr Corbyn was challenged about the allegations by a journalist from the Daily Mail during a question and answer session at the EEF manufacturers’ conference in London, where he had delivered the keynote speech.

He replied: “I am sorry the Daily Mail has reduced itself to reproducing some nonsense that was written in The  Sun.”

Asked directly by BBC Breakfast presenter Steph McGovern, who was acting as compere for the event, if he was a “Czech spy”, he said: “No.”

His denial came after he threatened Tory MP Ben Bradley with legal action over a tweet claiming he “sold British secrets to Communist spies”.

Mansfield MP Ben Bradley (Stefan Rousseau/PA)

According to the original Sun report, documents unearthed in the StB  archives showed that Mr Corbyn met a Czech agent on at least three occasions  – including twice in the House of Commons – during the 1980s and was given the codename Cob.

The Labour leader’s office acknowledged that he had had tea in the Commons with a Czech diplomat, but said any claim he was “an agent, asset or informer for any intelligence agency is entirely false and a ridiculous smear”.