BRUSSELS (AP) -- European Union and British negotiators failed to reach a breakthrough in Brexit talks during a frantic all-night session and will continue seeking a compromise on the eve of Thursday's crucial EU summit.
An EU official, who asked not to be identified because the negotiations were still ongoing, said Wednesday that "discussions continued until late in the night and will continue today."
Both sides were hoping that after more than three years of false starts and sudden reversals, a clean divorce deal for Britain leaving the bloc might be sketched out within the coming hours.
Even though many questions remain, diplomats made it clear that both sides were within touching distance of a deal for the first time since a U.K. withdrawal plan fell apart in the British House of Commons in March.
But talks saw no deal materializing between experts from both sides holed up late into the night at EU headquarters in Brussels.
British Prime Minister Boris Johnson's office said the negotiations had been "constructive" and would continue.
Johnson is eager to strike a deal at an EU summit starting Thursday that will allow for the U.K. to leave the bloc in good order on the scheduled date of Oct. 31, fulfilling his promise to get Brexit done, come what may.
But both sides say gaps remain over plans for keeping goods and people flowing freely across the Irish border, the thorniest issue in the talks.
An open border between EU member Ireland and the U.K.'s Northern Ireland underpins both the local economy and the 1998 peace accord that ended decades of Catholic-Protestant violence in Northern Ireland. But once Britain exits, that border will turn into an external EU frontier that the bloc wants to keep secure.
The big question is how far Johnson's government is prepared to budge on its insistence that the U.K., including Northern Ireland, must leave the European Union's customs union — something that would require checks on goods passing between the U.K. and the EU, including on the island of Ireland. Ireland and other EU members say any checks in Ireland are unacceptable.
The alternative is to have checks between Britain and Northern Ireland. But Northern Ireland's Democratic Unionist Party, the party that props up Johnson's minority government, strongly opposes any measures that could loosen the bonds between Northern Ireland and the rest of the U.K.
Even if there is a deal, it must be passed by both European lawmakers and Britain's Parliament, which rejected — three times — the agreement struck by his predecessor, Theresa May.
Pro-Brexit Conservative lawmaker David Davis said success rests on the stance of the DUP.
He said that "if the DUP says 'this is intolerable to us' that will be quite important."
This week's EU leaders' meeting — the last scheduled summit before the Brexit deadline — was long considered the last opportunity to approve a divorce agreement. Johnson insists his country will leave at the end of the month with or without an agreement, although U.K. lawmakers are determined to push for another delay rather than risk a chaotic no-deal Brexit.
They have passed a law that compels the government to ask the EU to postpone Brexit if there is no deal in place by Saturday.
Johnson insists he won't do that — but also says he will obey the law. It's unclear how the two statements can be reconciled.