Britain has been given until the end of Friday to come forward with fresh proposals to break the Brexit deadlock.
EU officials have said they are ready to work through the weekend if the UK comes forward with an “acceptable” plan to resolve the impasse over the Northern Ireland backstop, the BBC reported.
Theresa May is facing a crunch Commons vote on Tuesday when she takes her Brexit deal back to MPs following its overwhelming rejection in January by a majority of 230.
The Prime Minister has staked her hopes of getting through the “meaningful vote” this time on securing concessions from the EU on the backstop – which has proved the main stumbling block to an agreement.
Tory Brexiteers have been demanding legally-binding assurances the UK cannot be tied indefinitely to EU rules through the backstop, intended to prevent the return of a hard border on the island of Ireland.
However, talks in Brussels on Tuesday between the EU’s chief negotiator Michel Barnier and Attorney General Geoffrey Cox and Brexit Secretary Stephen Barclay broke up without agreement.
Both sides acknowledged that the meeting had been “difficult”, with reports Mr Barnier complained that Mr Cox had brought forward “a legal solution to a political problem”.
Philip Hammond warned Tory Brexiteers against voting down Mrs May’s deal next week, saying rejecting it would lead to a delay to Brexit.
“If the Prime Minister’s deal does not get approved on Tuesday then it is likely that the House of Commons will vote to extend the Article 50 procedure, to not leave the European Union without a deal, and where we go thereafter is highly uncertain,” he told BBC Radio 4’s Today programme.
“For those people who are passionate about ensuring that we leave the European Union on time it surely must be something that they need to think very, very carefully about now because they run the risk of us moving away from their preferred course of action if we don’t get this deal through on Tuesday.”
The Chancellor said he believed MPs would not support leaving the EU without a deal, but refused to be drawn on how he would vote if MPs are asked whether they want to delay Britain’s withdrawal.
“I’m not going to speculate about something that hasn’t happened and I don’t think will happen because I think the Government is very clear where the will of Parliament is on this,” he said.
“Parliament will vote not to leave the European Union without a deal next Wednesday, I have a high degree of confidence about that.”
Meanwhile, French Europe minister Nathalie Loiseau said the Withdrawal Agreement could not be reopened, and that it represented “best possible solution”.
“We cannot reopen this negotiation on the Withdrawal Agreement because it is balanced,” she told Today.
“We don’t like the backstop, we don’t want to have to implement it, and if we have to, we don’t want to stay in the backstop.
“We all agree that it should be temporary, and that it’s a last resort solution.”