Britain has all but given up on a special Brexit summit at the end of November as there remain too many sticking points to complete the talks in the time originally hoped for.

UK and EU negotiators were talking until 2.45am on Monday night, Downing Street said, but sources downplayed the prospect of any immediate breakthrough as the impasse on the Irish border backstop continues.

Negotiations will continue intensively this week, but unless there is dramatic progress by the end of Wednesday, there can be no European summit to sign off a draft deal this month. “There’s no breakthrough at the moment,” a Whitehall source said.

The absence of a breakthrough means Tuesday’s scheduled cabinet meeting will not be the substantive discussion intended to sign off the UK’s Brexit negotiating position as had been expected. It will note developments and discuss no-deal planning instead.

A Brexit deal could be signed off at the European Union’s scheduled summit in December, on the 13 and 14, which would leave little time to squeeze in a parliamentary vote to ratify the agreement before Christmas.

A few minutes earlier, Michel Barnier, said a breakthrough had not been achieved in the latest intensive negotiations with the British over the weekend.

During a short meeting in Brussels, Barnier told European affairs ministers for the 27 EU members that the negotiators had so far failed to the make the decisive progress needed on the Irish border issue.

“Barnier explained that intense negotiating efforts continue, but an agreement has not been reached yet,” a statement said.

UK sources had spoken last week of a hope that Dominic Raab, the Brexit secretary, could make a visit to Brussels on Tuesday to unveil a deal and prepare the way for a Brexit summit. But Number 10 said on Monday morning that there were no plans for him to travel to Brussels for the moment.

If an agreement can be secured in the next 36 hours, a November summit could still be convened by Donald Tusk, the president of the European Council, leading to the publication of both the withdrawal agreement and the political declaration on the future relationship. May wants to secure a November summit to ensure there is enough time for the British parliament to ratify a deal.

EU capitals, however, want time to examine any agreement made between the European Commission and the UK before it is published.

In the meeting with Barnier, about 10-12 member states intervened, stressing the need for national capitals to be able to scrutinise any Brexit deal, including the political declaration on the future. Ministers also welcomed continued no-deal planning and stressed that the EU had to remain united.

To avoid a hard border on the island of Ireland ever emerging, the government is proposing a temporary UK-wide customs union to be in place until another solution is believed possible by Whitehall.

The EU is, in turn, insisting the UK could not unilaterally withdraw from such an agreement if Whitehall decided that another border solution was possible.

Brussels is also demanding that the UK sign up to “dynamic” alignment with future environmental, social and labor regulations, which would in effect force parliament to cut and paste EU diktats into British law.

A commitment on the side of the British to provide the European fishing fleet with access to UK seas after Brexit has also been proposed by member states as a condition for agreement on the customs union.

Michael Roth, Germany’s minister of state for the EU, said the member states had made “many compromises but the room for maneuver is very much limited and our British friends know exactly where our discussions are”.

Belgium’s deputy prime minister, Didier Reynders, told reporters: “We have time but not so much, so for this moment it’s very difficult to make real progress but before Christmas, I’m hoping that it will be possible.

“Of course we are prepared for all the different possibilities but we try to work hard on a good agreement and we are very close, you know what are the limits for the moment.

“About Ireland, we have made a proposal with some evolutions in the last days but until now we don’t have a positive signal about that so I’m hoping this will be the case in the next weeks but certainly not today.”

With concerns growing that the prime minister’s timetable is slipping, the pound fell on Monday morning by 0.8% to $1.2827, an 11-day low.

Nathalie Loiseau, the French EU minister, said there had been intensive discussions and Brussels was working to avoid a no-deal scenario, which she stressed was primarily important for the UK.

She said: “I have no crystal ball, unfortunately. We will have a close look at what a customs union would mean for us because it’s in between the withdrawal agreement and the future relationship so of course, it’s a little bit special to discuss the two of it. We are ready, we are open but of course we want to see the details.

“If we end any sort of temporary arrangement this is to be a bilateral decision from the EU27 and from the UK at the same time and we have to know in that moment what sort of solution there is for the Irish border.”

With the UK cabinet yet to back May’s plan for a customs union, Aleš Chmelař, the Czech Republic’s Europe minister, suggested the logjam was at the political level rather than between the negotiators.

He said: “I still hope that we will have a decision soon on decisive progress in the negotiations but it is to be seen whether we hold a summit before December or not.

“We’ve all seen some technical possibilities on the compromise, it is now a matter of political agreement. I’m still hopeful that we can have decisive progress this month.”