William Wragg, chair of the public administration and constitutional affairs committee, said a "number of MPs have faced intimidation" in recent days after declaring, or assumed to have declared, their desire for a vote of confidence in the PM.

He told the committee it is "not the function" of the government whips office to breach the ministerial code by "threatening to withdraw investments in constituencies funded by the public purse".

Whips 'blackmailing MPs and encouraging embarrassing stories'

Mr Wragg accused the whips of "encouraging the publication of stories in the press seeking to embarrass those that they suspect of lacking confidence in their prime minister".

He added that "intimidation of a member of parliament is a serious matter" and the reports he has been told of "would seem to constitute blackmail".

MPs who have been threatened with alleged blackmail should contact the Speaker of the House and the head of the Metropolitan Police, Dame Cressida Dick, Mr Wragg said.

"It is of course the duty of the government whips office to secure the government's business in the House of Commons," he said.

"However, it is not their function to breach the ministerial code in threatening to withdraw investments from members of parliament's constituency which are funded from the public purse."

Mr Wragg is one of a handful of Conservatives who have publicly called for Mr Johnson to go over the Downing Street lockdown parties scandal but he did not reveal if he had been intimidated or blackmailed by the whips office.

MP who defected 'faced intimidation from whips office'

His intervention comes a day after Bury South MP Christian Wakeford defected from the Conservatives to Labour.

Mr Wakeford had been one of the Tory MPs who had submitted a letter of no confidence in Mr Johnson and was said to have been "hauled" in by the Tory chief whip the night before.

A Conservative MP told Sky News it sent him over the edge when they threatened his seat" with having its boundary changed.

"This is what bully tactics look like," the MP said.

Labour's deputy leader Angela Rayner said the accusations by Mr Wragg are "shocking" and said: "We need this to be investigated thoroughly."