British Prime Minister Boris Johnson’s troubles have worsened after another senior member of his government abruptly quit – the latest in a string of departures on Wednesday.

Alex Chalk resigned as solicitor-general for England and Wales, saying he could not “defend the indefensible”.

“To be in government is to accept the duty to argue for difficult or even unpopular policy positions where that serves the broader national interest. But it cannot extend to defending the indefensible,” Mr Chalk wrote in his resignation letter to Mr Johnson.

“Public confidence in the ability of No.10 [Downing Street] to uphold the standards of candour expected of a British government has irretrievably broken down. I regret that I share that judgement.

“This comes at a moment of intense challenge for our country, when trust in government can rarely have been more important. I’m afraid the time has therefore come for fresh leadership.”

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It was the latest in a flurry of resignations late on Tuesday and into Wednesday, including Rishi Sunak’s departure as chancellor and Sajid Javid’s resignation as health secretary.

Four other MPs quit junior government roles while a trade envoy stood down and a vice-chairman of the Conservative Party resigned his post on live television.

Catherine Haddon from the Institute for Government think tank told the BBC she expected Mr Johnson would have “a really, really difficult day” on Wednesday. “More awkwardness” was to be expected, she said.

“It will certainly be more people publishing letters and probably more of an idea of an eventual timetable for a vote of confidence,” she said.

“It’s going to be a febrile day.”

But other senior figures expressed their support for Mr Johnson. Foreign minister Liz Truss, considered a leading contender to replace him, said she was “100 per cent behind the PM”.

The resignations followed months of scandals and missteps, with Mr Johnson so far weathering criticism over a damning report into parties at his Downing Street residence and office that broke COVID-19 lockdown rules and saw him fined by police.

They leave him facing the biggest crisis of his leadership. But, signalling his intention to stay in power for as long as possible, Mr Johnson quickly appointed former businessman and his previous education minister Nadhim Zahawi as his new finance minister.

Steve Barclay, who was appointed to impose discipline in Mr Johnson’s administration in February, was moved to the health portfolio.

The resignations came as Mr Johnson was apologising for appointing an MP to a role involved in offering pastoral care, even after being briefed that the politician had been the subject of complaints about sexual misconduct.

There have been other policy U-turns, an ill-advised defence of another politician who broke lobbying rules, and he has also come under fire for not doing enough to tackle a cost-of-living crisis, with many Britons struggling to cope with rising fuel and food prices.

Mr Sunak and Mr Javid had previously publicly supported Mr Johnson, but in their letters said enough was enough.

“The public rightly expect government to be conducted properly, competently and seriously,” Mr Sunak said.

“I recognise this may be my last ministerial job, but I believe these standards are worth fighting for.”

Mr Javid said many MPs and the public had lost confidence in Mr Johnson’s ability to govern in the national interest.

“It is clear to me that this situation will not change under your leadership – and you have therefore lost my confidence too,” his letter said.

The resignations came minutes after Mr Johnson apologised on television for appointing MP Christopher Pincher to a role involved in offering pastoral care in the Conservative Party, his latest public expression of contrition for his mistakes.

“I just want to make absolutely clear that there’s no place in this government for anybody who is predatory or who abuses their position of power,” Mr Johnson said.

Mr Pincher’s resignation last Thursday triggered days of a changing narrative from Downing Street over what Mr Johnson knew of the deputy chief whip’s behaviour and when he knew it.

Earlier on Tuesday, after a former top official accused Mr Johnson’s office of lying, the PM’s spokesman was forced into a quick about-turn to say Mr Johnson had been briefed in “some form” about the case but had forgotten about that last week.

Some Conservative politicians are trying to renew attempts to unseat him, a month after Mr Johnson survived a confidence vote, while others earlier appealed to his cabinet ministers to move against him.

“He’s finished,” one previously loyal Conservative politician said, on condition of anonymity.

“He shouldn’t prolong the agony. It’s disrespectful to his colleagues, his party and his country.”

Opposition Labour leader Keir Starmer said those who had backed Mr Johnson were complicit in how he had performed his job.

“After all the sleaze, the scandals and the failure, it’s clear that this government is now collapsing,” he said.

-with AAP