Weekend negotiations aimed at finding an acceptable divorce settlement between the EU and the UK ahead of next March’s Brexit deadline once again failed after the two sides could not come to an agreement over the future of the land border between European Union member Ireland and Northern Ireland, which will join the rest of the United Kingdom when it leaves the bloc.

After UK sources confirmed the British Brexit negotiating chief Dominic Raab had arrived in Brussels to meet with his EU counterpart Michel Barnier for snap negotiations on Sunday afternoon, an EU ambassadors’ Committee of Permanent Representatives meeting was confirmed for two and a half hours later, giving the initial impression that a staff level agreement was in the works.

“With several big issues still to resolve, including the Northern Ireland backstop, it was jointly agreed that face-to-face talks were necessary ahead of this week’s October European Council,” said an EU spokesperson in a statement, which echoed Barnier’s own tweet, which said, “We [Dominic Raab and Barnier] met today and UK negotiating team. Despite intense efforts, some key issues are still open, including the backstop for Ireland / Northern Ireland to avoid a hard border. I will debrief the EU27 and the European Parliament on the Brexit negotiations.”

British negotiators also agreed that no deal had been reached the weekend talks, with a British official familiar with negotiations confirming that the main sticking point remains the question over the border between Ireland and the North.

The clock is ticking for the two sides to come to some sort of resolution ahead of an October 17 deadline that is set to coincide with a European Council engagement, where the agreement is to be discussed approaches.

According to an EU diplomat who was present at the Committee of Permanent Representatives meeting said that a deal on the Irish border would be the sign that a major breakthrough had been reached.