Boris Johnson has resigned as Foreign Secretary amid a growing political crisis over the UK’s Brexit strategy.
He is the second senior cabinet minister to quit within hours following Brexit Secretary David Davis’s exit.
His departure came shortly before Theresa May began addressing Parliament about her new Brexit plan, which has angered many Conservative MPs.
She said she did not agree with the two ex-ministers about “the best way to honour” the result of the 2016 vote.
The BBC’s political editor Laura Kuenssberg said Mr Johnson’s exit had turned an “embarrassing and difficult situation for the PM into potentially a full-blown crisis”, fuelling speculation about a leadership challenge.
Ahead of a meeting of Tory MPs at 17.30 BST, Mrs May’s official spokesman said she would fight any attempt to oust her if the required 48 Tory MPs called for a contest.
Whispers Tory MP s have reached the magic number of the 48 letters required to force a confidence vote – no way of knowing yet if true – meeting at 5.30
— Laura Kuenssberg (@bbclaurak) July 9, 2018
No 10 said it will not reconsider the Chequers Brexit plan signed off by ministers on Friday but Laura Kuenssberg said she had been told by a source that either Theresa May “dumps” it or “another minister will go, then another, then another, then another”.
The UK is due to leave the European Union on 29 March 2019, but the two sides have yet to agree how trade will work between the UK and the EU afterwards.
There have been differences within the Conservatives over how far the UK should prioritise the economy by compromising on issues such as leaving the remit of the European Court of Justice and ending free movement of people.
Theresa May only has a majority in Parliament with the support of the 10 MPs from Northern Ireland’s Democratic Unionist Party, so any split raises questions about whether her plan could survive a Commons vote.