Here is a list of everyone who has resigned from the government so far (last updated 4.40pm):
Rishi Sunak resigns from Chancellor role
Mr Sunak said “the public rightly expect government to be conducted properly, competently and seriously”, adding: “I believe these standards are worth fighting for and that is why I am resigning.”
Sajid Javid quits as health secretary
Mr Javid said the British people “expect integrity from their government” but voters now believed Mr Johnson’s administration was neither competent nor “acting in the national interest”.
Alex Chalk resigns from solicitor general for England and Wales post
The top law figure said government posts "cannot extend to defending the indefensible".
His resignation letter added: “The cumulative effect of the Owen Paterson debacle, Partygate and now the handling of the former deputy chief whip’s resignation, is that public confidence in the ability of Number 10 to uphold the standards of candour expected of a British government has irretrievable broken down."
John Glen quits as Treasury minister
Mr Glen told Boris Johnson: "I can no longer reconcile my commitment to the role” with “the complete lack of confidence I have in your continuing leadership of our country”.
Will Quince resigned as children and families minister
The MP, who appeared on television earlier this week defending Boris Johnson, said inaccurate briefings given to him by No 10 left him "no choice" but to resign.
His letter read: “It is with great sadness and regret that I feel that I have no choice but to tender my resignation as minister for children and families as I accepted and repeated those assurances in good faith."
Robin Walker quit as schools standards minister
He said the Conservative party became "distracted from its core missions by a relentless focus on questions over leadership”.
He told Mr Johnson the “great achievements” of the Government had been “overshadowed by mistakes and questions about integrity”.
Victoria Atkins resigned as a justice minister
She said she could "no longer pirouette around our fractured values” and “we can and must be better than this”.
Jo Churchilll resigned as a minister at the Department for Environment, Food and Rural Affairs
The MP quit Defra after "recent events have shown that integrity, competence and judgment are all essential to the role of prime minister, while a jocular, self-serving approach is bound to have its limitations”.
Stuart Andrew resigned as housing minister
The MP took said he had to have a look at his own personal integrity and "given recent events" he had "no choice" but to resign.
Bim Afolami resigns as Tory vice-chair
Mr Afolami, who resigned on Tuesday as Boris Johnson no longer had his support, said Downing Street’s handling of the Chris Pincher scandal had been “appalling”.
Ministers Kemi Badenoch, Julia Lopez, Lee Rowley, Neil O’Brien and Alex Burghart resign in joint letter
They said "the Government cannot function” as they called for Boris Johnson to step down.
“It is with great regret that we are resigning as members of the Government. It has been an honour to serve in your administration and we remain extremely grateful for the opportunity you have given us to serve our country,” they wrote.
Mims Davies has also resigned as employment minister
She said the work that is being done in her department, and many others, was being "utterly overshadowed by what has unfolded from the heart of the government in Downing Street".
Rachel Maclean quit as safeguarding minister
"Values, principles, integrity and decency matter more than anything and I cannot continue to stand by and do nothing," she said.
Mike Freer, the minister for Exports and Equalities has quit.
He says he feels that the Tories "are moving away from the One Nation Conservative party I joined, not least in creating an atmosphere of hostility for LGBT+ people. And I regret I can no longer defend policies I fundamentally disagree with."
Parliamentary private secretaries/ministerial aides to quit
Jonathan Gullis quits as parliamentary private secretary to the Secretary of State for Northern Ireland
He said that the party he had been a member of his “entire adult life” had “been more focused on dealing with out reputation damage rather than delivering for the people of this country and spreading opportunity for all”.
“It is for this reason I can no longer to (sic) serve as part of your government.”
Saqib Bhatti quits as parliamentary private secretary to the Health Secretary
The MP quit his role with a statement that “recent events have undermined trust and standards in public life”.
“I have been grappling with these issues for some time and my conscience will not allow me to continue to support this administration,” he added.
Nicola Richards quits as parliamentary private secretary to the Department for Transport
She said in a statement that she could not serve “under the current circumstances”.
“At a time where my constituents are worried about the cost of living and I am ding my best to support them, I cannot bring myself to serve as a PPS under the current circumstances, where the focus is skewed by poor judgement that I don’t wish to be associated with.”
Virginia Crosbie resigns from parliamentary private secretary at the Welsh Office role
Ms Crosbie said Crosbie wrote that she was “forced to say the sheer number of allegations of impropriety and illegality” centred around Downing Street and Mr Johnson’s premiership made his position untenable.
Laura Trott resigns from PPS role to the Department for Transport
Announcing her resignation, she said: "Trust in politics is – and must always be – of the upmost importance, but sadly in recent months this has been lost."
Felicity Buchan quits as PPS at the Department of Business, Energy and Industrial Strategy
In her letter of resignation, Kensington MP Felicity Buchan told Boris Johnson: “You have lost the confidence of my constituents and me. The current situation is untenable.”
Selaine Saxby resigns as a ministerial aide
The Tory MP said that “with much regret” she “can no longer continue” in her role as a parliamentary private secretary for the Treasury.
Claire Coutinho resigns as parliamentary private secretary to the Treasury
She said: “I firmly believe that what we need now, as we deal with the twin challenges of war in Europe and global inflation, is a laser-like grip on reforming our public services so that they work better for our constituents and focus on charting a path to prosperity through what is an increasingly challenging global outlook.
David Johnston quit as a ministerial aide in the Department for Education
The Wantage MP said recent events have worsened the public's view of politics and politicians.
He said: “I cannot defend what has taken place these past few days – or indeed these past few months.”
Mark Logan quit as PPS at the Northern Ireland Office
The MP told the Prime Minister he did deserve a second chance, but added that "there is only so much anyone can expect my constituents to accept or ignore".
Craig Williams quits as PPS to the Chancellor
He said it had become "impossible" for the party to "draw a line under previous events and focus on rebuilding trust with the public".
Duncan Baker quits as PPS at Michael Gove's Department for Levelling Up
"The breakdown in trust from the last six months is abundantly clear," he said.
Mark Fletcher resigned as PPS for the Department for Business, Energy and Industrial Strategy
The MP accused Boris Johnson of being “an apologist for someone who committed sexual assault”.
Other roles
MP Theo Clarke resigns as the Prime Minister’s trade envoy to Kenya
The MP said she was "shocked to see colleagues defending the Government with assurances that have turned out to be false".
"This is not the way that any responsible Government should act," she added.
Andrew Murrison quits as trade envoy to Morocco
He said he was quitting as a result of the “rolling chaos of the past six months”.