EU to publish first draft of Brexit treaty
The European Union is set to publish a legal draft of its Brexit withdrawal agreement for the first time, detailing the terms of the UK's departure.
The draft document is expected to say Northern Ireland would have to follow EU single market rules to avoid a "hard border", if alternatives are not found.
Downing Street has dismissed any prospect of a return to a hard border.
The prime minister's coalition ally in Northern Ireland has threatened to withdraw support over the issue.
The Democratic Unionist Party said details of the draft treaty "fundamentally breached" an agreement reached in Brussels late last year.
"If the EU or Dublin believes the UK government will be signing up to a border in the Irish Sea, they are deluded," said senior DUP member Sir Jeffrey Donaldson.
Mr Donaldson argued the draft divorce treaty would also undermine the constitutional status of Northern Ireland in the Belfast Agreement.
That 1998 treaty - also known as the Good Friday Agreement - between the British and Irish governments and most political parties in Northern Ireland decided how the region would be governed and brought an end to 30 years of sectarian conflict.
The EU commissioners' 120-page draft Brexit withdrawal document will refer to three possible options for avoiding physical infrastructure on the Irish border.
However, the only one to be fleshed out will be the government's least-favourite: the option of Northern Ireland staying within the EU customs union and aligned with European rules and regulations, says BBC Brussels reporter Adam Fleming.
The document will encapsulate - in legally binding language - agreements already reached on Ireland, citizens' rights and the UK's so-called "divorce bill".
It mandates that during the Brexit transition, which it says should last only until the end of 2020, the UK must continue to comply with all existing EU legislation. It would however lose all voting rights and decision-making power, including on any rules adopted by the 27 remaining member states.
Leaked letter
EU negotiator Michel Barnier has said the document will not contain any surprises because it translates the political pledges made by both sides in the talks so far.
"The clock is ticking; time is short," Barnier said at a news conference on Tuesday. "I am concerned."
According to reports by Irish broadcaster RTE, the text will say that Northern Ireland may be considered part of European Union customs territory after Brexit, alluding to a single "regulatory space" on the island of Ireland with no internal barriers.
On Tuesday, a leaked letter from Foreign Secretary Boris Johnson appeared to accept the possibility of future customs border checks on the island of Ireland after the UK leaves the EU.
In the letter, obtained by Sky News, the foreign secretary tells Theresa May 95% of traffic would still pass unchecked if there was a hard border.
Earlier, Mr Johnson was criticised by opponents for suggesting in a BBC interview the issue of the border could be managed as easily as London's congestion charging zone.
In his letter to the prime minister, Mr Johnson seeks to play down the "exaggerated impression" of "how important checks are" at EU external borders.
Following the letter's emergence, Labour called for Mr Johnson - one of the leading Brexiteers in the cabinet - to be dismissed "before he can do any more damage".
A spokesman for Mr Johnson said the letter was "designed to outline how a highly facilitated border would work and help to make a successful Brexit".
"The letter points out there is a border now, and the task the (cabinet Brexit) committee face is stopping this becoming significantly harder," he said.
"It shows how we could manage a border without infrastructure or related checks and controls while protecting UK, Northern Ireland, Irish and EU interests."
