Another Conservative MP has called for Boris Johnson to resign as the turmoil at 10 Downing Street continues.
Former minister Nick Gibb is the latest Tory to submit a letter of no confidence in the prime minister.
He said his constituents were furious that No 10 had been “flagrantly disregarding” the Covid rules they set.
Meanwhile, the Daily Mirror reports a photograph of Mr Johnson holding a beer at a birthday gathering has been handed to police investigating Covid breaches.
The paper said the picture is one of 300 submitted to the Metropolitan Police investigation into 12 alleged gatherings and is thought to have been taken by the PM’s official photographer, who is funded by the taxpayer.
It says it shows the prime minister holding a can of beer at an event in No 10’s Cabinet Room in June 2020, alongside Chancellor Rishi Sunak, who was holding a soft drink.
At the time, gatherings of more than two people inside were banned by law.
Writing in the Daily Telegraph, Mr Gibb, who has served under three prime ministers and who lost his position as schools minister in Boris Johnson’s reshuffle last September, said his constituents were “furious about the double standards” and that “to restore trust, we need to change the prime minister”.
He said Covid restrictions imposed by Boris Johnson were “flagrantly disregarded” in Downing Street, and the PM was inaccurate when, in December, he told the House of Commons there was no party.
“Some argue that eating a few canapes with a glass of prosecco is hardly a reason to resign. But telling the truth matters, and nowhere more so than in the House of Commons where, like a court of law, truth must be told regardless of the personal consequences,” he wrote.
Mr Gibb said fellow backbench Tory Aaron Bell had “struck a chord” when he criticised Mr Johnson over lockdown parties earlier this week.
On Friday, Mr Bell said the “breach of trust” over the rule breaking and how it had been handled made the PM’s position untenable, as he confirmed he had also submitted a letter of no confidence to Sir Graham Brady – the chair of the 1922 Committee.
A leadership contest could be triggered if 54 letters are submitted.
Other Conservative MPs are expected to consider whether to put in their letters over the weekend.
Speaking on Newsnight, Conservative MP Andrew Bridgen suggested it was now the job of the cabinet to “show leadership” and “confront” the issue of the prime minister’s leadership.
But his fellow Tory MP Richard Bacon suggested that it was not for politicians to change governments – that was for the electorate to take care of.
Mr Johnson has written to all Tory MPs to say he is committed to improving the way 10 Downing Street works.
Some of his supporters, including one former cabinet minister, have criticised the chancellor Rishi Sunak, who this week distanced himself from the prime minister’s controversial comments about Sir Keir Starmer, for being disloyal at a difficult time.
No 10 policy chief Munira Mirza quit on Thursday, describing Mr Johnson’s comments on Sir Keir as “scurrilous”.
The prime minister falsely claimed that the Labour leader had failed to prosecute paedophile Jimmy Savile during his time as director of public prosecutions.
Mr Sunak said he “wouldn’t have said it”, while on Friday Health Secretary Sajid Javid said Sir Keir “did a good job and should be respected for it”.