World Bulletin / News Desk

British-ruled Northern Ireland could stay in a customs union with the EU after Brexit, the bloc's chief negotiator Michel Barnier said as he unveiled a draft divorce treaty on Wednesday.

London has rejected any measure that would effectively create a customs border between Northern Ireland and the rest of the UK, but the former French minister insisted the plan did not threaten British sovereignty.

"My personal opinion is that this backstop will not call into question the constitutional or institutional order of the UK," he said.

"I'm not trying to provoke, I'm not trying to create any shockwaves," Barnier added, calling on Britain to "keep calm and stay pragmatic".

The draft withdrawal agreement says that in the absence of another plan, "a common regulatory area comprising the Union and the United Kingdom in respect of Northern Ireland" would be set up.

"The common regulatory area shall constitute an area without internal borders in which the free movement of goods is ensured and North-South cooperation," it says.

Ireland and the EU have called for any Brexit agreement to avoid a hard border including customs checks, in order to protect the 1998 Good Friday peace agreement in Northern Ireland. 

Barnier also warned that Brexit talks must accelerate if they are to succeed, warning time was running out to agree the final text and have it ratified by both sides.

"If we wish to make a success of these negotiations -- and I certainly do -- we must pick up the pace," he said.