British Prime Minister Theresa May is battling at home to keep the last week's deal alive and push it through the British parliament amid criticism from pro-Brexit politicians, Northern Ireland's unionists and those who want to keep closer EU ties.

"No deal better than the one on the table can be reached," Germany's European affairs minister, Michael Roth, said. Economy minister Peter Altmaier also dismissed any prospect of a return to the drafting table.

More than two years after Britons voted in a 2016 referendum to leave the EU, the sides have reached a tentative divorce agreement and are working on an outline of their future ties to accompany that.

Though the fate of the accord is unclear on the British side, the EU is preparing for a summit next Sunday of all its national leaders that is meant to rubber-stamp the agreement.

They are also advancing their contingency planning for the scenario of a no-deal Brexit in which the sides would fail to seal their agreement and the United Kingdom is cut off on March 29, 2019, with very little in place to mitigate the economic and other disruptions.

"Any deal is better than no deal," Luxembourg's Foreign Minister Jean Asselborn told reporters on arrival to talks of national EU ministers about Brexit in Brussels. "I think that it's in the interests of the United Kingdom and the European Union...that this deal becomes reality."

Belgium's Didier Reynders echoed that and the Netherlands' Stef Blok called for an "ambitious" vision of the EU-British future ties in the political declaration that the sides are working on now to accompany the divorce deal.

"We hope that we will not have to reopen negotiations," the Czech Republic's Ales Chmelar said

Reporting by Jan Strupczewski, Daphne Psaledakis, Gabriela Baczynska