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".

There have been growing calls for Mr Johnson to stand down amid anger among his MPs over parties and gatherings in Downing Street during coronavirus restrictions in 2020 and 2021.

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MP who defected claims he was threatened

Christian Wakeford, the MP who defected from the Tories to Labour yesterday, said he was threatened by the whips. The Labour Party said it was over a vote on free school meals.

"I was threatened that I would not get the school for Radcliffe if I did not vote in one particular way. This is a town that's not had a high school for the best party of 10 years," he said.

Mr Wakeford had been one of the Tory MPs who 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 he defected.

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.

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 constituencies 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 lockdown parties scandal, but he did not reveal if he had been intimidated or blackmailed by the whips office.

The PM said he had seen "no evidence to support any of those allegations" but "of course" he would look at any evidence presented to him.

'Mafia tactics'

Lib Dem MP Alistair Carmichael brought Mr Wragg's statement up in the Commons, saying he had had "never heard" of this type of behaviour before and said it was more the tactics of "the mafia" than parliament.

Speaker Sir Lindsay Hoyle replied by saying they are "serious allegations" and reminded whips they "are not above the criminal law" and any allegations should be investigated by the police, without his interference.

He warned it is "contempt to obstruct members in the discharge of their duty or to attempt to intimidate a member in their parliamentary conduct by threats".

There is a "clear process" for dealing with these matters, he said as he told any MPs with concerns should write to him.

A Downing Street spokesman said: "We are not aware of any evidence to support what are clearly serious allegations.

"If there is any evidence to support these claims we would look at it very carefully."

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MP who defected 'faced intimidation from whips office'

Mr Wragg's 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 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.

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