The European Union has confirmed "no further meetings are foreseen" with the UK on updating Theresa May's Brexit deal - as negotiations have concluded.
A spokeswoman for European Commission president Jean-Claude Juncker said the leaders of the remaining 27 countries "have been very clear" that what is on the table "will not be renegotiated".
The comments are a blow to the British Prime Minister, who is trying to get concessions on the Northern Irish backstop plans in her Withdrawal Agreement in the hope that it will convince MPs to vote it through Parliament later this month.
At a press conference in Brussels this morning, Mina Andreeva, deputy chief spokeswoman for the European Commission, was asked what talks will be held before the Commons has its say on the deal on the week of 14 January.
She said: "We have said many times the deal that is on the table is the best and only deal possible. And the EU27 leaders confirmed on December 13 in their conclusions that it will not be renegotiated."
Ms Andreeva said the EU side have "started the ratification process" on the terms in the Withdrawal Agreement, adding: "For now, no further meetings are foreseen between the commission's negotiators and the UK negotiators as the negotiations have indeed been concluded."
She said Mr Juncker is "always willing to listen Mrs May's views on the backstop", but when asked what else he can do to help her deal get through Parliament, she rebuffed any chance of altering the backstop as it currently stands.
Ms Andreeva said: "We are not renegotiating what is on the table, our solutions are on the table, we are ready to listen but at this stage there are no further meetings and the EU 27 leaders have been very clear that it will not be renegotiated, what is on the table."
She said that, in a newspaper interview at the end of December, President Juncker "reiterated very clearly that we have put all the solutions on the table and now it is up the British people and MPs to decide on the next steps".
Her words come after Britain's Brexit Secretary warned that no deal will be "far more likely if MPs reject the government's Brexit deal later this month".
Writing in the Daily Express, Stephen Barclay said: "There is obviously division in Parliament over the PM's Brexit deal. It's not a perfect deal.
"But it's the only workable deal that delivers on the democratic choice of the British people. And it's the best way to avoid no-deal. As we return to Parliament, MPs must consider the alternative."
The Cabinet minister also confirmed the government is to "accelerate our no-deal planning further", adding: "The pace and intensity of the work we are doing reflects the potential scale of this disruption to people and businesses across the UK that a no-deal scenario could bring."
He added: "And, on Tuesday, we will start a new phase in our public information campaign, using radio and social media to further raise awareness about the need to prepare."
Meanwhile, Mr Barclay is reported to be convening a meeting today of ministers to discuss the latest preparations for a no-deal Brexit.
British Foreign Secretary Jeremy Hunt, speaking in Singapore, said cancelling Brexit through a second EU referendum would have "devastating" social consequences, while a no-deal exit would cause economic disruption.
He predicted that the UK government would "find a way" of getting the 585-page withdrawal agreement approved by parliament.
Mrs May has been urged to delay the "meaningful vote" on her Brexit deal for a second time.
Former Brexit secretary David Davis has speculated the vote could be put off if Mrs May looks likely to lose it.