The Labour leader was said to have spoken to the Czech at least three times, including twice in the House of Commons during the height of the Cold War.
Mr Corbyn was also alleged to have warned him about British intelligence activity – claims described as showing “breathtaking naivety”.
The meetings happened in 1986 after Mr Corbyn had been vetted by communists from the state now dissolved into Czech Republic and Slovakia.
Secret files, seen by The Sun, allegedly show Mr Corbyn passed on material about the arrest of an East German and was subsequently put on a list of Czechoslovakian state security team’s agents.
However, a spokesman for the Labour Party has dismissed the report saying that Mr Corbyn met with a Czech diplomat but the Labour leader not offer any privileged information.
The records show that Mr Corbyn was “negative towards USA, as well as the current politics of the Conservative Government”.
Expert Professor Anthony Glees of the Oxford Intelligence Group said: “It shows breathtaking naivety from someone who wants to head the British Government.”
Mr Glees added: “These files show Jeremy Corbyn had been targeted by Czech intelligence services.
“These files shows there was contact between Corbyn and a Czech intelligence official, even if he did not know it.
“At the time dissidents were under attack and being imprisoned in Czechoslovakia.
In the struggle between the dissidents who were trying to overthrow the communist government and the Czech government, Corbyn is working on the side of the Czech government.
“The Czechs were interested in anti-communists and they are using Corbyn for immediate operational information useful to them.
” The records were found in the archives of the Czech secret police in Prague and they are likely to have been seen by the Russian President Vladimir Putin.
A Labour Party spokesman said: “The claim that Jeremy Corbyn was an agent, asset or informer for any intelligence agency is entirely false and a ridiculous smear.
“Like other MPs, Jeremy has met diplomats from many countries. In the 1980s he met a Czech diplomat, who did not go by the name of Jan Dymic, for a cup of tea in the House of Commons. Jeremy neither had nor offered any privileged information to this or any other diplomat.
“During the Cold War, intelligence officers notoriously claimed to their superiors to have recruited people they had merely met.
“The existence of these bogus claims does not make them in any way true, as The Sunday Times found out to its cost when it published fabricated allegations about former Labour leader Michael Foot and the KGB.”