The chancellor, who quit moments after Mr Javid, 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 PM, 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 for Boris Johnson': Double blow for Johnson - Politics live

The pair's 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 the fact ministers were briefed to tell the media this morning the PM did not know about a previous allegation against Mr Pincher - when he did - was what pushed them over the edge.

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

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: Rishi Sunak and Sajid Javid's resignation letters in full

'This government is now collapsing'

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," he 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 and "strongly" urged Mr Johnson to step down. He said the "last straw in the rolling chaos" was former senior civil servant Lord McDonald this morning saying Mr Johnson had lied about not knowing Mr Pincher had faced previous allegations.

Bim Afolami then quit as the Conservative Party's vice-chair, Jonathan Gullis resigned as a parliamentary private secretary to the Northern Ireland secretary and Saqib Bhatti quit as a parliamentary private secretary to the department of health and social care.

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 minister stand behind PM

Following the resignations today, 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" as 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."