Labour leader Jeremy Corbyn has announced a new cabinet following a wave of resignations in protest at his leadership and amid calls to resign.
He lost 12 of his shadow cabinet on Sunday, another on Monday, and several shadow ministers. Most criticised his EU referendum campaign input.
Mr Corbyn said he regretted the walkouts but pledged to stand in any new leadership election.
Labour MPs are due to discuss a no confidence motion against Mr Corbyn.
Many of the party's MPs have been critical of Mr Corbyn's leadership since his election in September, when he won a landslide victory despite starting the contest as a rank outsider.
The shadow cabinet shake-up sees Emily Thornberry - who on Sunday gave her backing to Mr Corbyn - moved from shadow defence secretary to shadow foreign secretary, replacing Hilary Benn who was sacked at the weekend.
Meanwhile, Diane Abbott - an ally of the Labour leader - has been promoted from shadow international development secretary to shadow health secretary, a position vacated by Heidi Alexander's resignation.
The new appointments include:
- Shadow foreign secretary - Emily Thornberry
- Shadow health secretary - Diane Abbott
- Shadow education secretary - Pat Glass
- Shadow transport secretary - Andy McDonald
- Shadow defence secretary - Clive Lewis
- Shadow chief secretary to the Treasury - Rebecca Long-Bailey
- Shadow international development secretary - Kate Osamor
- Shadow environment food and rural affairs secretary - Rachel Maskell
- Shadow voter engagement and youth affairs - Cat Smith
- Shadow Northern Ireland secretary - Dave Anderson
The latest frontbench resignations came on Monday, by shadow Welsh secretary Nia Griffiths, shadow foreign minister Diana Johnson, shadow civil society minister Anna Turley and shadow defence minister Toby Perkins,.
Wayne David, the shadow Cabinet Office, Scotland and justice minister, has also quit, along with shadow consumer affairs and science minister Yvonne Fovargue and shadow environment minister Alex Cunningham.
Several shadow ministerial aides have also stepped down, including Stephen Kinnock, Neil Coyle and Jess Phillips.
The motion of no confidence in Mr Corbyn was submitted by Labour MPs Dame Margaret Hodge and Ann Coffey, and a secret ballot could be held on Tuesday.
Mr Corbyn has said he would fight for his job, warning: "Those who want to change Labour's leadership will have to stand in a democratic election, in which I will be a candidate."
He also said he had been elected as leader with "an overwhelming mandate for a different kind of politics".
"I am not going to betray the trust of those who voted for me - or the millions of supporters across the country who need Labour to represent them," he added.
"Neither wing of the Tory government has an exit plan. Labour will now ensure that our reform agenda is at the heart of the negotiations that lie ahead.
"One clear message from last Thursday's vote is that millions of people feel shut out of a political and economic system that has let them down and scarred our country with grotesque levels of inequality."
In other developments:
- George Osborne has said the UK is ready to face the future "from a position of strength" in a bid to calm markets after the surprise Brexit vote triggered turmoil on Friday
- The pound fell in early trading in Asia on Monday, adding to Friday's record one-day decline
- Potential Tory leadership contender Boris Johnson says the UK will continue to "intensify" co-operation with the EU following the country's vote to leave
- Prime Minister David Cameron will chair the first meeting of the cabinet since the EU referendum result. It is not a political cabinet and Mr Johnson will not be there
- The executive of the 1922 Committee of backbench Tory MPs is set to meet to draw up the timetable for the Tory leadership contest
- German Chancellor Angela Merkel and French President Francois Hollande will hold talks later in Berlin to discuss the fallout of Brexit
- Scotland's First Minister Nicola Sturgeon says Holyrood could try to block the UK's exit from the EU
- The House of Commons petitions committee says it is investigating allegations of fraud in connection with a petition calling for a second EU referendum
- Former Conservative leader and Brexit campaigner Iain Duncan Smith told the BBC the new prime minister should come from the Leave camp
The mass resignations were triggered by the sacking of shadow foreign secretary Hilary Benn, in the early hours of Sunday, after he told Mr Corbyn he had lost confidence in him.
Speaking on Sunday's Andrew Marr Show, Mr Benn - who has ruled out any Labour leadership bid - said Mr Corbyn was "a good and decent man but he is not a leader".
In a parting shot, Mr Bryant warned Mr Corbyn that he was in danger of going down in history as "the man who broke the Labour Party".
In his resignation later, Mr Kinnock, parliamentary aide to shadow business secretary Angela Eagle, said he had reached the conclusion following the EU referendum result that Mr Corbyn was "no longer able to lead our party" and did not have "the requisite skills or experience" to steer Labour through the period ahead.
But shadow chancellor John McDonnell and shadow cabinet members Andy Burnham, Diane Abbott and Emily Thornberry have all rallied around Mr Corbyn.
Ms Thornberry told the BBC's Victoria Derbyshire programme that now was not the time for Labour to be "plunged in to turmoil".
"We have to hold our nerve and think very carefully for the sake of the country as to what happens next," she said, and called on the party to "stick behind" the leader.
Mr McDonnell told Sunday's Pienaar's Politics: "Jeremy is not going anywhere and will continue on."
Meanwhile, deputy Labour leader Tom Watson said he was "deeply disappointed" that Mr Benn had been sacked and "equally saddened" by the shadow cabinet resignations.
He said his focus was to "hold the Labour Party together in very turbulent times" and that he would meet Mr Corbyn on Monday to discuss the "way forward".
Those who resigned from Labour's top team on Sunday were:
- Lord Falconer, shadow justice secretary
- Chris Bryant, shadow leader of the House of Commons
- Heidi Alexander, shadow health secretary
- Lucy Powell, shadow education secretary
- Vernon Coaker, shadow Northern Ireland secretary
- Ian Murray, shadow Scottish secretary - and Labour's only MP in Scotland
- Kerry McCarthy, shadow environment secretary
- Seema Malhotra, shadow chief secretary to the Treasury
- Lillian Greenwood, shadow transport secretary
- Gloria de Piero, shadow minister for young people and voter registration
- Diana Johnson, shadow foreign minister
- Anna Turley, shadow civil society minister
- Toby Perkins, shadow defence minister
Karl Turner, the shadow attorney general who is not in the shadow cabinet but attends meeting, also quit.
A number of senior trade unionists on Labour's ruling national executive committee rallied in support of Mr Corbyn - including Unite leader Len McCluskey and Dave Ward of the Communication Workers Union.
And more than 200,000 people have signed an online petition backing the Labour leader, who was elected last September in a landslide victory.
The Labour Party campaigned for Remain during the referendum, which saw the UK voting to leave the EU by 52% to 48% on Thursday.
But Mr Corbyn - who has been a long-standing critic of the EU and who is regarded as the most Eurosceptic Labour leader in years - has been accused by some in his party of not making the case for the EU forcefully enough.