MPs regularly meet diplomats who they assume are spies, a shadow cabinet minister has said as he defended Jeremy Corbyn’s attack on the press over a series of stories about his Cold War past.

The Labour leader has flatly denied that he was a spy for Czechoslovakia during the Cold War and warned right-wing newspapers that “change is coming” following reports on his alleged association with an agent of the communist country.

Shadow international trade secretary Barry Gardiner said the claims, which originally appeared in The Sun, that Mr Corbyn passed information to an agent of the Czech StB intelligence agency during the 1980s were “incredibly stupid”.

According to the original 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”.

Mr Corbyn is facing pressure to outline why he met the diplomat, but Mr Gardiner said MPs routinely hold similar meetings.

The shadow international trade secretary told BBC Radio 4’s Today programme: “All politicians are meeting diplomats every day of the week and some of us assume that half the people that we meet from foreign embassies are spies, we just assume that.

“So of course you know that if people are coming from the embassy that there is a possibility that they are spies, it doesn’t mean that you’re not a patriot, it doesn’t mean that you don’t do your job as a politician and stand up for this country, but equally of course you meet diplomats from every country around the world.”

Mr Gardiner also accused the press of attempting to “discredit” Mr Corbyn because they are “trying to get their revenge in” ahead of the second phase of the public press ethics inquiry.

He accused newspapers of running the stories because they are worried about the second phase of the Leveson Inquiry being triggered either by a Lords amendment to the Data Protection Bill or a Labour government.

Prime Minister Theresa May has promised to overturn the Lords amendment when the Bill comes before MPs in the Commons, warning it would “undermine high-quality journalism and a free press”.

Mr Gardiner said: “These smears are coming now because they know that that (Leveson) is coming back into the public forum and that’s exactly why the newspapers are trying to get their revenge in first, they are trying to discredit Jeremy.

“I mean, this is an incredibly stupid story to have (for) four days in national newspapers from a fantasist who’s recorded as telling his handlers in Prague that actually he was also responsible for the Live Aid concert, for the Nelson Mandela birthday concert.”

The Sun said it would continue to ask inconvenient questions regardless of “how many times we are threatened with ‘change'”.

A spokesman for The Sun said: “Over the past few days, we have revealed substantial, documented evidence from the Czech Security Archive that a Czech spy met with Jeremy Corbyn at the height of the Cold War.

“It is in the public interest to know how that meeting was arranged, why it was accepted, and what was discussed, particularly given what was known then and what we know now about the brutality of the Soviet-backed regime in Czechoslovakia.

“Those questions are yet to be answered and we will keep asking them, no matter how inconvenient they might be, nor how many times we are threatened with ‘change’ – whatever that may mean.

“They are questions that we would put to anybody who aspires to the highest office in the land.”