An umbrella is pictured during an anti-Brexit demonstration outside the Houses of Parliament, in Westminster, London, Britain January 29, 2019. REUTERS/Hannah Mckay

STOCKHOLM (Reuters) - Britain’s agreement on leaving the European Union is non-negotiable, Sweden’s EU minister said on Wednesday, underlining the problems UK Prime Minister Theresa May will have extracting concessions from Brussels in the coming weeks.

Sweden has historically been a close ally of Britain. They see eye-to-eye on issues such as free trade and reining in the EU’s budget. But Sweden’s EU minister, Hans Dahlgren, stressed unity among EU members in their view on Brexit.

“There is no room to negotiate on the exit agreement,” he told Reuters in an interview. “The backstop is a part of the exit agreement so it is clear (renegotiating) that is not on the cards.”

On Tuesday, British lawmakers demanded May return to Brussels to rework the exit agreement and replace the so-called Irish backstop, which aims to prevent a hard border between Ireland and Northern Ireland.

Politicians in the Irish Republic are opposed to changes, which could jeopardize the 1998 Good Friday Agreement that helped to end decades of violence in Ireland.

“We are solidly behind the Republic of Ireland,” Dahlgren said. “It’s not so many decades ago that there was a bloody conflict in the north. This cannot happen again.”

While there is no room to renegotiate the exit agreement, Dahlgren said, the EU was willing to talk about Britain’s future relationship with the bloc.

“If they don’t want what has been talked about up to now but want something else, more ambitious or whatever that may be, then there is an openness around that,” Dahlgren said.

If May cannot get a deal agreed, the default option would be to exit the EU abruptly with no deal at all.