Last-ditch Brexit negotiations between the UK and Brussels failed to reach a draft divorce settlement on Sunday due to the Northern Irish border issue just days before a crucial European Union summit, AFP reported.

British Brexit pointman Dominic Raab made an unannounced visit to the EU capital for talks with his counterpart Michel Barnier, briefly raising hopes that an agreement might be in sight.

But talks ended without a breakthrough, including on the issue of trade to and from Northern Ireland, which is seen as a potential deal breaker.

Diplomatic sources in Brussels confirmed to AFP that talks have been suspended until Wednesday, when the leaders of the other 27 EU member states will be in the Belgian capital on the eve of their October summit, which had already been billed as a “moment of truth.”

“We met today Dominic Raab and UK negotiating team. Despite intense efforts, some key issues are still open, including the backstop for IE/NI to avoid a hard border,” Barnier tweeted, referring to EU member Ireland and the British province of Northern Ireland.

Diplomatic sources confirmed that a meeting of the “diplomatic sherpas” – senior officials representing the leaders of EU members – that had been planned for Monday to review a draft agreement has been called off.

“The commission informed the ambassadors that no deal was reached today. There will be no further negotiations until the summit,” an anonymous source said.