Ministers, special advisers and staff at No.10 have been accused of seeking to blackmail and intimidate MPs to stop them from trying to force the prime minister out of office.
PACAC chair William Wragg, a senior Conservative MP, said MPs were being threatened with losing constituency funding or finding “embarrassing” stories about themselves in the press if they backed a vote of confidence in Boris Johnson over the Partygate scandal.
He said: “In recent days, a number of members of parliament have faced pressures and intimidation from members of the government because of their declared or assumed desire for a vote of confidence in the party leadership of the prime minister.
“It is of course the duty of the government whip's office to secure the government's business in the House of Commons. However, it is not their function to breach the ministerial code in threatening to withdraw investments from members of parliament's constituencies which are funded from the public purse.
“Additionally, reports to me and others of members of staff in No.10 Downing Street, special advisers, government ministers and others, encouraging the publication of stories in the press, seeking to embarrass those who they suspect of lacking confidence in the prime minister is simply unacceptable.
“The intimidation of a member of parliament is a serious matter. Moreover, the reports of which I'm aware would seem to constitute blackmail.”
Wragg urged any MPs who felt they had been targeted to contact the Met Police commissioner and the speaker of the House of Commons.
He also said MPs were welcome to contact him “at any time”.
Wragg was speaking at an evidence session this morning, before going on to quiz Cabinet Office minister Steve Barclary and permanent secretary Alex Chisholm on subjects including Greensill, Lord Geidt, the PPE VIP lane and diversity in public appointments.
Wragg asked Barclay to “convey the spirit of the statement to the government” and for Chisholm to ensure the civil service “would respond as necessary”, with both agreeing to do so.
Former Tory MP Christian Wakeford, who left the Conservatives yesterday to join Labour yesterday, has backed up Wragg's claims, telling the BBC he was told plans for a new high school in his constituency could be scrapped if he did not vote the right way.
Labour's deputy leader Angela Rayner called the claims "shocking" and Lib Dem leader Sir Ed Davey accused Johnson of "acting more like a mafia boss than a prime minister".
No.10 has denied Wragg's claims, with a spokesperson saying it is "not aware of any evidence to support what are clearly serious allegations".
The spokesman said No.10 would look "very carefully" at any evidence submitted to support the claims.
Some MPs are attempting to call a vote of no confidence in Johnson over lockdown parties held in Downing Street, with the PM asking rebels to await the outcome of Cabinet Office second perm sec Sue Gray's Partygate inquiry.
Wragg himself had previously called on Boris Johnson to resign over the Downing Street gatherings, saying MPs were "worn out of defending what is invariably indefensible".