The chancellor, who quit moments after Mr Javid shortly after 6pm, said: "The public rightly expect government to be conducted properly, competently and seriously. I recognise this may be my last ministerial job, but I believe these standards are worth fighting for and that is why I am resigning."

In his letter to the prime minister, Mr Javid said he could "no longer, in good conscience, continue serving in this government" as he referenced the tone and values of Mr Johnson reflecting "on your colleagues, your party and ultimately the country".

He added: "It is clear to me that this situation will not change under your leadership - and you have therefore lost my confidence too."

'Very, very grave': Double blow for PM - Politics live

Their resignations led several junior ministers to quit their posts in protest at Mr Johnson's leadership, while Alex Chalk resigned as solicitor general.

Mr Sunak was replaced as chancellor by Nadhim Zahawi, while Mr Javid was replaced as health secretary by Steve Barclay, the prime minister's chief of staff. Michelle Donelan was appointed as education secretary.

In his written reply to Mr Sunak, Mr Johnson said the chancellor had "provided outstanding service to the country through the most challenging period for our economy in peacetime history".

He also wrote to Mr Javid to say he would be "greatly missed" and added: "I look forward to your contribution from the backbenches."

A snap poll found seven in 10 Britons think Mr Johnson should resign, an 11-point increase on the number in favour of the prime minister's resignation when last asked on 9 June. The YouGov poll of more than 3,000 people also found just 21% said they thought Mr Johnson will resign.

The resignations came minutes after Mr Johnson gave an interview admitting he should not have appointed MP Chris Pincher as deputy chief whip in February after claims the MP groped two men last week.

Conservative MP Andrew Bridgen, who has publicly called for Mr Johnson to go over the past few months, told Sky News that the pair were pushed over the edge by the fact that ministers were briefed to tell the media on Tuesday morning that Mr Johnson did not know about a previous allegation against Mr Pincher - when he did.

"I and a lot of the party are determined he [Mr Johnson] should be gone by summer recess," Mr Bridgen said.

As the most senior person in government after the prime minister, Mr Sunak's resignation is a big blow to Mr Johnson while Mr Javid, who ran against Mr Johnson in the leadership election, has played a major role during the pandemic.

Sky News understands the pair had not coordinated their resignations but Mr Sunak may have already been preparing to step down and was prompted to this evening by Mr Javid's announcement.

There is a view by some MPs that they quit to launch their own leadership bids as they expect Mr Johnson will have to step down, despite the PM insisting on previous occasions he would be staying.

Read more:
Read Sunak and Javid's resignation letters in full

'This government is now collapsing'

Labour leader Sir Keir Starmer said "it's clear that this government is now collapsing" and accused Mr Javid and Mr Sunak of being "complicit" as Mr Johnson "has disgraced his office and let down his country".

"After all the sleaze, the scandals and the failure, it's clear that this government is now collapsing. Tory cabinet ministers have known all along who this prime minister is," the Labour leader said.

"They have been his cheerleaders throughout this sorry saga."

Shortly after the two cabinet ministers quit, Dr Andrew Murrison resigned as the PM's trade envoy to Morocco; Bim Afolami quit as the Conservative Party's vice-chair; Theo Clarke and Andrew Murrison resigned as trade envoys and ministerial aides Jonathan Gullis, Saqib Bhatti, Nicola Richards and Virginia Crosbie left their roles.

The resignations come a week after Oliver Dowden quit as Conservative Party chairman following major defeats in by-elections in Wakefield and Tiverton and Honiton. He cited voters being "distressed and disappointed by recent events, and I share their feelings".

Other cabinet ministers stand behind PM

After the resignations on Tuesday, the majority of remaining cabinet ministers have told Sky News they will not be quitting.

They include: Justice Secretary Dominic Raab, Business Secretary Kwasi Kwarteng, Home Secretary Priti Patel, Defence Secretary Ben Wallace, Housing Secretary Michael Gove, Foreign Secretary Liz Truss, Culture Secretary Nadine Dorries, Transport Secretary Grant Shapps, Attorney General Suella Braverman, International Trade Secretary Anne-Marie Trevelyan, Brexit Opportunities Minister Jacob Rees-Mogg, Work and Pensions Secretary Therese Coffey, Scotland Secretary Alister Jack, Northern Ireland Secretary Brandon Lewis and Wales Secretary Simon Hart.

Mr Javid added in his letter: "It is with enormous regret that I must tell you that I can no longer, in good conscience, continue serving in this government. I am instinctively a team player but the British people also rightly expect integrity from their government.

"The tone you set as a leader, and the values you represent, reflect on your colleagues, your party and ultimately the country.

"Conservatives at their best are seen as hard-headed decision-makers, guided by strong values. We may not have always been popular, but we have been competent in acting in the national interest.

"Sadly, in the current circumstances, the public are concluding that we are now neither.

"The vote of confidence last month showed that a large number of our colleagues agree. It was a moment for humility, grip and new direction. I regret to say, however, that it is clear to me that this situation will not change under your leadership - and you have therefore lost my confidence too."

Mr Sunak said in his letter he had "always tried to compromise" and on the occasions where he disagreed with Mr Johnson privately "I have supported you publicly".

He acknowledged stepping down as chancellor during the cost of living crisis, the effects of the pandemic and the war in Ukraine "is a decision that I have not taken lightly".

"I firmly believe the public are ready to hear that truth. Our people know that if something is too good to be true then it's not true," he said.

"They need to know that whilst there is a path to a better future, it is not an easy one. In preparation for our proposed joint speech on the economy next week, it has become clear to me that our approaches are fundamentally too different.

"I am sad to be leaving government but I have reluctantly come to the conclusion that we cannot continue like this."