And the hard-Left Labour leader issued a sinister threat to the media in a video posted on the internet last night, saying it should “fear” the prospect of his party taking power.
And he suggested a future government under his leadership would carry out sweeping media reforms to “open up” the industry, saying: “We’ve got news for them – change is coming.”
He went on the attack at a manufacturing bosses conference, rubbishing reports about his contacts in the 1980s with a Czech diplomat in London who was later expelled for espionage.
It followed days of claims by Jan Sarkocy of links between left-wing Labour MPs and the Czech secret service.
Quizzed after a speech to the EEF manufacturers association in Westminster, Mr Corbyn said they were “nonsense” and had been “reproduced” in newspaper reports.
Minutes later, he was asked by a BBC journalist: “Are you a Czech spy?”
Laughing, Mr Corbyn replied: “No”. “They [newspapers] have found a former Czechoslovakian spy whose claims are increasingly wild and entirely false. He seems to believe I kept him informed about what Margaret Thatcher had for breakfast and says he was responsible for either Live Aid or the Mandela concert, or maybe both.
“It’s easy to laugh, but something more serious is happening.
“Publishing these ridiculous smears that have been refuted by Czech officials shows just how worried the media bosses are by the prospect of a Labour government. They are right to be.
“Labour will stand up to the powerful and corrupt and take the side of the many, not the few.”
Mr Corbyn is under mounting pressure to authorise the release of Cold War files kept on him by the Stasi after Prime Minister Theresa May said he must be “open and transparent” about his links to former communist spies.
The Commons Foreign Affairs Committee is considering a request from Tory backbencher David Morris for Mr Corbyn to be questioned about the claims.
When asked about the allegations earlier this week, Mrs May said all MPs needed to “be accountable for their actions in the past”.
Mr Sarkocy has said he met Mr Corbyn at least three times in 1986 and 1987.
The then outspoken hard left backbencher was given the codename “Agent Cob” by Czech agents and was said to have “an active supply of information on British intelligence services”, he claimed.
Earlier this week Mr Corbyn’s spokesman said of the spy reports: “The claim that he 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. Jeremy neither had nor offered any privileged information to this or any other diplomat.”
Yesterday former Labour MP and ex-London mayor Ken Livingstone admitted meeting a KGB spy during the 1980s, but said Soviet agents “feared we were too left-wing”.
He said agents wanted to “sound out” him and Mr Corbyn about what they would do if they ever came to power in Britain.
Mr Livingstone recalled meeting a journalist from Soviet newspaper Pravda who he suspected was a KGB officer.
“If he had asked me to do anything, I mean I would have said no,” Mr Livingstone added.