British Prime Minister Boris Johnson is battling claims that Tory critics are facing "intimidation" which could amount to blackmail as part of an effort to keep him in office.
Mr Johnson insisted he had seen no evidence to support the claim made by William Wragg, the Tory chairman of the Commons Public Administration and Constitutional Affairs Committee.
Mr Wragg said he had received reports of conduct including "members of staff at 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".
"The intimidation of a Member of Parliament is a serious matter. Reports of which I am aware would seem to constitute blackmail," he said at the start of a Commons committee hearing.
"As such it would be my general advice to colleagues to report these matters to the Speaker of the House of Commons and the Commissioner of Metropolitan Police."
But Mr Johnson, on a visit to Taunton, said: "I've seen no evidence to support any of those allegations.
"What I am focused on is what we're doing to deal with the number one priority of the British people, which is coming through Covid."
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Mr Wragg is one of a handful of Tory MPs to have said publicly they have submitted a letter to the chairman of the backbench 1922 Committee, Sir Graham Brady, calling for a no-confidence vote in Mr Johnson's leadership.
He said the conduct of the Government Whips' Office threatening to withdraw public funding from MPs' constituencies may have breached the ministerial code.
Meanwhile, Scotland's First Minister Nicola Sturgeon called for an inquiry to be launched into the claims, while Scottish Conservative leader Douglas Ross - who has called for the Prime Minister to resign over the Downing Street parties scandal - said he is disappointed in the allegations but has not experienced any intimidation himself.
Ms Sturgeon told ITV Border: "These are gravely serious allegations - intimidation, blackmail and using public money to do it.
"I would suggest that these accusations need to be fully and, crucially, independently investigated.
"With everyday right now, Boris Johnson is tarnishing the office of Prime Minister and I think if he has concerns for the interests of the country, he will go."