FILE PHOTO: European Council President Donald Tusk arrives for the second day of a NATO summit in Brussels, Belgium, July 12, 2018. Tatyana Zenkovich/Pool via REUTERS

BRUSSELS (Reuters) - European Council President Donald Tusk said on Monday that the 27 states remaining in the bloc after Britain leaves must be ready for a no-deal Brexit, a scenario he said was “more likely than ever before”.

With less than six months to go before Britain’s departure, talks stalled at the weekend over how to ensure there is no return to a hard border between the British province of Northern Ireland and EU-member Ireland.

Tusk said all parties must do their best to reach a deal, adding that he had invited British Prime Minister Theresa May to address her 27 EU peers on Brexit on Wednesday evening, the first day of a two-day summit of EU leaders he will chair.

“The fact that we are preparing for a no-deal scenario must not, under any circumstances, lead us away from making every effort to reach the best agreement possible ... Let us not give up,” Tusk said in an invitation letter to the summit.

“Later at 27, we will decide on how to take the negotiations forward, on the basis of a recommendation by our chief negotiator, Michel Barnier,” Tusk said in the letter.

“It has proven to be more complicated than some may have expected. We should nevertheless remain hopeful and determined, as there is good will to continue these talks on both sides,” he said.

The stalemate in the negotiations has increased the possibility of Britain leaving the bloc without an agreement, a “no deal Brexit” which could potentially cause disruptions to trade and delay movement of goods.