LONDON: British Prime Minister Boris Johnson was fighting on Friday to shore up his authority after a senior aide resigned over his false claim that the leader of the opposition Labour Party failed to prosecute a notorious child sex abuser.

Johnson, who in 2019 won the biggest Conservative majority since Margaret Thatcher, has repeatedly refused to resign over revelations that he and some of his staff attended Downing Street parties during COVID lockdowns.

Those revelations raised questions about Johnson's often chaotic style of leadership and have led to the greatest threat to him since he took office. They follow a series of other scandals.

Johnson admitted that problems needed to be fixed at the heart of Downing Street, which serves as both his home and the nerve centre of the British state.

Munira Mirza, his head of policy who had worked with him for 14 years, resigned on Thursday over Johnson's claim that Labour leader Keir Starmer failed to prosecute paedophile Jimmy Savile during his time as director of public prosecutions (DPP).

Johnson's finance minister, Rishi Sunak, said pointedly that he would not have made such a remark. Starmer has cast Johnson's comment as a ridiculous slur - and conspiracy theory - that shows Johnson is unfit to be British leader.

Ministers presented three additional resignations which followed Mirza as evidence that Johnson was fixing the problems at Downing Street and "taking charge", though there remained considerable anger at Johnson within his own party.

"I'm deeply troubled by what's going on," Huw Merriman, a Conservative lawmaker who chairs the transport select committee, told BBC radio.

Merriman said that if a prime minister did not shape up then he would have to go, adding that many Conservative voters were upset and saddened about recent events at the highest levels of the British state.

A member of Johnson's policy unit also quit on Friday, the editor of the Conservative Home website said. Downing Street declined immediate comment.

While opposition parties and some of Johnson's own lawmakers have called on him to quit, there is concern that toppling a British leader at this juncture would leave the West weakened as it faces a potential military crisis in Ukraine.

With inflation soaring at the fastest rate in 30 years, anger at the government is likely to deepen ahead of the May local election.

Leading rivals within the Conservative Party include Chancellor of the Exchequer Sunak, 41, and Foreign Secretary Liz Truss, 46.

To trigger a leadership challenge, 54 of the 360 Conservative MPs in parliament must write letters of no confidence to the chairman of the party's 1922 Committee.

A snap poll by YouGov conducted on Jan. 31 showed that 63% of voters wanted Johnson to resign, though another YouGov poll showed just 31% thought he would resign.

Asked what was going on in Downing Street, junior energy minister Greg Hands told Sky: "Resignations have been made, resignations have been accepted."

"This is the prime minister taking charge," he said.