Theresa May's Cabinet has given its blessing to a draft agreement on the terms for Britain's withdrawal from the European Union, as well as an outline political declaration on the future relationship.

The agreement was announced by the Prime Minister on the steps of 10 Downing Street after a marathon five-hour meeting of Cabinet which stretched on far beyond its expected time.

The move clears the way for a special Brexit summit in Brussels - probably on November 25 - for EU leaders to approve the deal, followed by a crucial Commons vote in which MPs will hold Britain's future in their hands.

Speaking moments after the meeting's conclusion, Mrs May acknowledged there would be "difficult days ahead" and announced she will outline the deal to MPs in the House of Commons on Thursday.

And she added: "This is a decisive step which enables us to move on and finalise the deal in the days ahead.

"These decisions were not taken lightly but I believe it is a decision that is firmly in the national interest."

She concluded: "I firmly believe, with my head and my heart, that this is a decision which is in the best interests of the United Kingdom."

Senior ministers met amid a storm of condemnation for the proposed deal from Brexit-backing Tories, with prominent Leaver Peter Bone warning Mrs May in the House of Commons that she risked losing the support of "many Conservative MPs and millions of voters across the country".

Meanwhile, Arlene Foster, whose DUP party props up Mrs May's minority administration in the Commons, warned the PM there would be "consequences" if her deal treats Northern Ireland differently from the rest of the UK.

The level of Brexiteer discontent has raised expectations of further letters of no confidence in Mrs May from Tory MPs, with a total of 48 needed to trigger a vote on her position.

Sources within Westminster said the delivery of letters to the chair of the backbench 1922 Committee Sir Graham Brady was "imminent".

Mrs May described the debate around the famous Cabinet table as "long, detailed and impassioned", in an apparent indication that her proposals had come under intense challenge from ministers.

But predicted resignations did not materialise, as Mrs May said ministers had come to a "collective decision" to back the 500-page document agreed by UK and EU negotiators in Brussels.

Speaking against the backdrop of boos and shouts from anti-Brexit campaigners on Whitehall, she said: "When you strip away the detail the choice before us is clear - this deal which delivers on the vote of the referendum, which brings back control of our money, laws and borders, ends free movement, protects jobs, security and our Union, or leave with no deal or no Brexit at all."

Earlier, she had urged Cabinet ministers to act in the national interest and support a Brexit deal which takes the UK "significantly closer" to delivering the result of the referendum.

She faced a crunch showdown with Brexit-backing ministers as she seeks to persuade her senior team to back a draft deal on the UK's withdrawal from the European Union.

Tensions over the proposed agreement were heightened by reports that a senior Brussels negotiator has said the deal will mean the UK aligns its rules with Europe, while the EU "will retain all the controls".

At Prime Minister's Questions, Mrs May told MPs: "The Cabinet will decide on the next steps in the national interest.

"I am confident that this takes us significantly closer to delivering what the British people voted for in the referendum.

"We will take back control of our borders, our laws and our money, leave the Common Fisheries Policy and the Common Agricultural Policy while protecting jobs, security and the integrity of our United Kingdom."

Irish premier Leo Varadkar said the draft deal could provide the basis for a summit of EU leaders by the end of the month, potentially on November 25.

"It is yet to be agreed by the UK Government and they will discuss it this afternoon, and it is yet to be agreed by the European Council, and we may be in a position to have an emergency European Council meeting before the end of the month to do exactly that," he said.

Amid feverish speculation about possible Cabinet resignations, Leave-backing Conservatives including Boris Johnson and Jacob Rees-Mogg called on ministers to reject the proposed agreement, which they fear could lock Britain in the EU's customs union indefinitely, blocking its ability to strike new trade deals elsewhere.

DUP leader Arlene Foster headed for London with a warning that she would not back a deal which leaves Northern Ireland "adrift in the future".

A leaked diplomatic note obtained by The Times suggested that Sabine Weyand - deputy to EU chief negotiator Michel Barnier - told ambassadors the UK "would have to swallow a link between access to products and fisheries in future agreements" and it also indicated that close customs alignment should remain indefinitely.

According to the note, Ms Weyand said: "We should be in the best negotiation position for the future relationship. This requires the customs union as the basis of the future relationship.

"They must align their rules but the EU will retain all the controls. They apply the same rules. UK wants a lot more from future relationship, so EU retains its leverage."

The draft agreement is understood to involve the UK remaining in a customs union and committing to a "level playing field" on EU rules in areas like environmental and workplace protections during a backstop period after Brexit.

In an apparent response to Ms Weyand's comments, the Prime Minister said: "I am aware of the concerns that there are, that we don't want to be in a position where the European Union would find it comfortable to keep the UK in the backstop permanently.

"That's why any backstop has to be temporary."

The "backstop" is intended as a fallback arrangement to avoid a hard border with Ireland unless a wider trade agreement can resolve the issue.

Brussels is understood to have dropped its demand for Northern Ireland alone to remain within the EU customs area until a new trade deal is implemented, but the province could be subject to a different regulatory regime.

The Guardian reported that an independent arbitration committee will judge when the backstop could be terminated, with a review six months before the end of the separate transition period in December 2020.

At Westminster, speculation over possible resignations focused on Brexit-backing ministers such as Penny Mordaunt, Andrea Leadsom and Esther McVey.

Sources close to Brexiteer ministers played down the prospect of walkouts, saying "don't expect fireworks today".

Mrs Leadsom told ITV's Good Morning Britain she had had "a good conversation" with the Prime Minister and was "extremely optimistic that we'll have a good deal", while Ms Mordaunt is understood to be still waiting for more information about the proposals.

Former Tory leader Lord Hague warned Brexiteers that if they did not accept Mrs May's deal, Britain might not leave the EU.

He told BBC Radio 4's Today programme: "If you are those sceptics, the ardent Brexiteers, what you have to really worry about here is that if you don't take this opportunity to leave the EU, to get Brexit over the line, you might never leave at all."

Former Brexit secretary David Davis urged his former Cabinet colleagues to "say no to this capitulation", while Mr Johnson said they should "chuck it out", warning that the proposals made a "nonsense of Brexit".

Brexit-backing Tory MP Andrew Bridgen said: "This isn't Brexit, it's not even close to Brexit.

"If it were darts, it's not missing the board, this is not even the right wall."