Ireland will see a new "hard border" spring up with the North if Britain fails to approve a Brexit withdrawal deal with the European Union, Brussels warned on Tuesday

EU commission spokesman Margaritis Schinas said he had heard nothing new since British Prime Minister Theresa May's laid out a tweaked divorce plan on Monday.

"If you'd like to push me and speculate on what might happen in a no-deal scenario in Ireland, I think it is pretty obvious: you will have a hard border," he said.

A new physical frontier between the British province and the Irish Republic would increase the threat that Brexit poses to the peace deal that ended decades of unrest.

Schinas also expressed frustration as journalists questioned him over the next steps in the negotiation.

"In all honesty, I have a terrible sense of deja vu in all these exchanges," he said. "There is nothing else that I can meaningfully say."

On Monday, May appeared before a British parliament anxious to hear a "Plan B" after lawmakers rejected the withdrawal agreement she signed with Europe last year.

Instead, she promised to seek changes to the accord to push back the prospect of Europe invoking a "back stop" clause that would keep Britain in the EU customs union.

"I will not now speculate on this Plan B because, as I said seconds ago, we are for Plan A, which is set by the withdrawal agreement," Schinas said.

The back stop insurance policy in the agreement that May welcomed in November is intended to prevent the return of a border between Northern Ireland and Ireland.

European leaders have repeatedly warned they will not re-open the withdrawal agreement, raising fears Britain will leave the bloc without a deal on March 29