Boris Johnson has branded suggestions he may have taken part in further rule-breaking during the pandemic “a load of absolute nonsense”.

The former prime minister would not say who he believes is trying to “stitch him up”, having previously claimed he appears to be the victim of a politically motivated plot.

But he insisted that the Cabinet Office decision to hand over entries from his official diary during the pandemic to police without first querying them with him was “ridiculous”.

No 10 and the Cabinet Office are adamant that ministers were not involved when Whitehall officials passed concerns to the Metropolitan Police and Thames Valley Police.

The entries revealed visits by Johnson’s friends to Chequers – the prime minister’s country estate – and events in Downing Street during the pandemic, according to The Times, which broke the story.

The new information is said to have come to light during a review by taxpayer-funded lawyers ahead of the Covid public inquiry.

Johnson was catching a flight in Washington DC on Friday as part of his trip to the US, where he is speaking about the war in Ukraine, when he was approached by a Sky News journalist asking about the revelations.

“You want my honest view, I think this whole thing is completely nonsensical,” he said.

Asked what the entries show, he replied: “They merely record events in my day.”

Johnson was previously fined for attending a gathering in Downing Street to mark his birthday in June 2020 – one of a series of political crises that ultimately led to the end of his premiership.

“This whole thing is a load of nonsense from beginning to end… I think it’s ridiculous that elements in my diary should be cherry-picked and handed over to the police, to the Privileges Committee without even anybody having the basic common sense to ask me what these entries referred to,” he said.

Asked whether he believes Sunak is trying to stitch him up, he said: “I just think it’s totally nonsensical and bizarre. There are tens of thousands of entries in the prime ministerial diary… None of them constitute a breach of the rules during Covid.”

Johnson suggested none of the entries in question relate to periods when the country was in lockdown, but times when other restrictions were in place.

He added: “For reasons that – somebody, somewhere, thinks it’s sensible to do this – I don’t.”

The privileges committee, which is conducting an inquiry into whether Johnson lied to Parliament about the partygate scandal, has also been informed of the new information.

The fallout adds to the problems confronting Sunak, who was handed a fixed penalty alongside Johnson over the June 2020 event and now faces unrest from the former prime minister’s allies.

Sunak “definitely” did not go to the grace-and-favour retreat in contravention of coronavirus rules when he was chancellor during the pandemic, his press secretary said.

The rime minister has not discussed the controversy with his predecessor, the spokeswoman said.

Johnson, in a letter to the chair of the Covid inquiry, indicated he was severing ties with taxpayer-funded lawyers representing him.

It is understood he lost confidence in the Cabinet Office.

Labour leader Keir Starmer said earlier on Friday the public was “fed up to the back teeth” with stories about the former prime minister.

“These are deeply personal things and increasing revelations about Boris Johnson, I think, just add to that sense of hurt and people are fed up with it,” he said.

“I do think there are questions now about why have these allegations not come out before, all these allegations.