BRUSSELS (Reuters) - The European Union on Monday warned Britain time was running out to seal a Brexit deal this autumn and ensure London does not crash out of the bloc next March, adding to pressure on Prime Minister Theresa May.

May’s spokesman, however, said the “focus is on getting this right” rather than meeting a deadline.

The EU’s Brexit negotiator Michel Barnier told 27 ministers of the bloc meeting in Brussels on Monday that “no significant progress” had been made in negotiations with London since March, the Bulgarian chairwoman of the talks said.

Diplomats and officials in Brussels have raised doubts about whether the bloc and London will be able to mark a milestone in the negotiations at the summit of EU leaders on June 28-29.

“More work is needed to prepare for the UK’s orderly withdrawal... Allow me to repeat myself: we are not there yet,” Barnier said on Monday, adding the outstanding issues, including the Irish border conundrum, were “very serious”.

The current schedule puts progress in June as an important step towards a final Brexit deal in October, which would leave enough time for an elaborate EU ratification process before the Brexit day.

“October is only five months from now and still some key issues related to the withdrawal agreement need to be settled. In June we need to see substantive progress on Ireland, on governance and all remaining separation issues,” said Ekaterina Zakharieva, deputy prime minister of Bulgaria which holds the EU’s rotating presidency.

German, Austrian and Dutch ministers all echoed the same concern, saying Britain has not made its position clear in detail on parts of the negotiations: “The clock is ticking,” Germany’s Michael Roth told his EU peers.

“We need now to be making substantial progress, but that is not happening. What is worrying us in particular is the Northern Ireland question where we expect a substantial accommodation from the British side.”

At home, May is stuck between a rock and a hard place with staunch Brexit supporters pushing to sever ties with the EU and others advocating keeping close customs cooperation with the bloc to reduce frictions in future trade.

May’s spokesman said London was working on two options for post-Brexit customs cooperation.

Under a customs partnership, Britain could collect tariffs on the EU’s behalf. Under a second idea, for a streamlined customs arrangement, traders on an approved list would be able to cross borders freely with the aid of automated technology.

While both sides want to continue close cooperation on internal security and foreign policy after Brexit, even this area, previously seen as an easy part of the unprecedented divorce negotiations, has seen a series of recent hiccups.

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Britain and the EU have clashed over the Galileo satellite project, and the bloc has criticised London for what it called its lackadaisical use of a key travel and crime database.

PRESSURE

The EU has said London must come up with a solution for the Irish border and highlights that has not happened. Both sides worry that reinstating a physical border between EU-member Ireland and Britain’s province of Northern Ireland - including to manage customs - could revive violence there.

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Other outstanding issues include guarantees for expatriate rights and trade rules after Brexit.

With May’s cabinet, her ruling Conservative party and the British public split down the middle on Brexit, the prime minister has come under increasing pressure to make a decision on customs.

The Brexit schedule is tightening, Brussels sources said, which helps the EU to pile pressure on London before the June summit but is mostly due to lack of real progress in the talks.

Dutch Foreign Minister Stef Blok said it was too early to discuss an extension of the timeline, but added: “The aim is now to conclude a deal in the time schedule that has been agreed on ... I very much hope we will agree but there are no guarantees, unfortunately.”