European Union leaders on Sunday approved a historic Brexit deal with British Prime Minister Theresa May, and together warned rebellious MPs in London this was the best and only option available.
Leaders meeting at a special Brussels summit expressed sadness at the "tragic" end of four decades of British EU membership, but said the terms of the withdrawal were now set.
"This is the best deal possible for Britain, this is the best deal possible for Europe," European Commission President Jean-Claude Juncker said after the agreement was approved.
TRT World's Simon McGregor-Wood reports from Brussels.
'Certainly not be renegotiated'
Juncker emphasised that, after 17 months of grueling negotiations, "this is the only deal possible", warning: "Those who think by rejecting the deal, they will have a better deal, will be disappointed."
The agreement prepares for Britain's smooth exit on March 29, 2019, and sets out a vision for "as close as possible a partnership " afterwards.
But May faces a major battle to get the agreement through the House of Commons, with a vote planned for next month.
MPs of all parties –– including her own Conservatives –– say they will oppose it, with many holding out hope of a better alternative.
"It will certainly not be renegotiated and there will be no further room for manoeuvre," said Austrian Chancellor Sebastian Kurz, whose country holds the rotating EU presidency.
May herself repeated this, telling reporters in Brussels: "This is the best possible deal, it's the only possible deal."
"If people think there is somehow another negotiation to be done, that is not the case," she told reporters after EU leaders approved the divorce text.
"This is the deal that is on the table, this is the best possible deal, it's the only possible deal."
While May hailed the deal, Juncker said the UK’s departure was a tragedy.
"It's a sad day," Juncker said as he arrived at the summit.
He told reporters that deal was "the best possible," but the summit "is neither a time of jubilation nor of celebration. It's a sad moment, and it's a tragedy."
"This is a historic summit and also historic day that evokes ambivalent feelings," said German Chancellor Angela Merkel.
"It is tragic that Great Britain is leaving the EU after 45 years."
In a formal statement endorsing the deal, the bloc called on EU institutions "to take the necessary steps to ensure that the agreement can enter into force on 30 March 2019, so as to provide for an orderly withdrawal."
EU chief negotiator Michel Barnier said now that the first phase was done, Britain and the EU needed to work for "an ambitious and unprecedented partnership."
"Now is the time for everybody to take their responsibility — everybody," he said.
Dutch Prime Minister Mark Rutte said the deal — the product of a year and a half of often grueling negotiations between Britain and the EU — was regrettable, but acceptable.
"I believe that nobody is winning. We are all losing because of the UK leaving," Rutte said. "But given that context, this is a balanced outcome with no political winners."
The last big obstacle to a deal was overcome on Saturday, when Spain lifted its objections over the disputed British territory of Gibraltar.
The deal must still be ratified by the European Parliament, something parliament President Antonio Tajani said was likely in January.
More dauntingly for May, it also needs approval from Britain’s Parliament.
May is under intense pressure from pro-Brexit and pro-EU British lawmakers, with large numbers on both sides of the debate opposing the divorce deal and threatening to vote it down when it comes to the House of Commons next month.
Brexiteers think it will leave the UK tied too closely to EU rules, while pro-Europeans say it will erect new barriers between Britain and the bloc — its neighbour and biggest trading partner.
May insists her deal delivers on the things that matter most to pro-Brexit voters — control of budgets, immigration policy and laws — while retaining close ties to the UK’s European neighbours.
'A miserable failure'
Britain's main opposition Labour Party will oppose the government's Brexit deal in parliament, its leader Jeremy Corbyn said on Sunday, describing the agreement approved in Brussels as "a miserable failure of negotiation".
"This is a bad deal for the country. It is the result of a miserable failure of negotiation that leaves us with the worst of all worlds. It gives us less say over our future, and puts jobs and living standards at risk," Corbyn said in a statement.
"That is why Labour will oppose this deal in parliament. We will work with others to block a no deal outcome, and ensure that Labour's alternative plan for a sensible deal to bring the country together is on the table."