Barnier presses UK to present Irish border solution

"It is urgent to work on the text of an operational backstop. For that, I asked Dominic and his team to provide us with the data necessary for the technical work which we need to do now on the nature, location, and modality of the controls that will be necessary," Barnier said.

The EU coined the backstop option that would practically keep Northern Ireland in the EU's customs union and the single market for goods to avoid a hard border on the island of Ireland, a commitment the UK has also agreed to.

"This backstop is critical. It's essential to conclude negotiations because, with no backstop, there can be no agreement [on Brexit]," Barnier warned.

But London has so far rejected the idea of the backstop, saying it would create a border between Northern Ireland and the rest of the UK.

"The solutions must be workable. They must be workable for the communities living in Northern Ireland, and living in the Republic of Ireland, for people affected in their daily lives," Raab said at the joint press conference.

The backstop would come into effect if no other solutions were found to avoid a hard border.

'Unprecedented'

The EU wants to highlight the possibilities of close and ambitious cooperation with the UK after Brexit to make swallowing the backstop option a bit easier for London.

Barnier emphasised again that the EU and UK were working for an "unprecedented partnership" in the future that would include a free trade agreement, cooperation in areas of internal security, foreign policy, external security, and defence.

"It's unprecedented, such a partnership with a third country," Barnier said.

"But the preliminary condition to that is that we have to organise an orderly withdrawal of the UK. That's the condition of the unprecedented partnership in the future," warned the French politician.

He added that it was "possible" to get an agreement in time for an October summit of EU leaders in Brussels, but added that a delay was possible. EU officials say an extraordinary meeting of EU leaders to seal Brexit is likely in November.

Raab said he was "stubbornly optimistic" that there would be a deal on Brexit.