The UK could unilaterally leave the customs union after Brexit, the EU's chief negotiator Michel Barnier said on Friday.
He made the comment in a bid to make the Brexit deal more acceptable to the UK parliament.
However, he said that Britain woud still need to honour its commitment to preserve a border free of controls between Northern Ireland and the Republic.
Barnier took to Twitter to update people on the ongoing talks with the UK after his briefing with ambassadors of the 27 EU states that are staying on together after Brexit.
In a series of social media posts, he said: "The EU has proposed to the UK a legally binding interpretation of the #Brexit Withdrawal Agreement," Most importantly, he continues:
"2/5 The arbitration panel can already, under Article 178 WA, give UK the right to a proportionate suspension of its obligations under the backstop, as a last resort, if EU breaches its best endeavours/good faith obligations to negotiate alternative solutions.
"3/5 EU ready to give legal force to all commitments from January letter of @eucopresident and @JunckerEU through joint interpretative statement. https://europa.eu/!Kj44wR This will render best endeavour/good faith obligations even more actionable by an arbitration panel.
"4/5 EU commits to give UK the option to exit the Single Customs Territory unilaterally, while the other elements of the backstop must be maintained to avoid a hard border. UK will not be forced into customs union against its will.
"5/5 The EU will continue working intensively over the coming days to ensure that the UK leaves the EU with an agreement," he concludes.
The Deputy Leader of the Democratic Unionst Party, Nigel Dodds, said in a tweet that Barnier was not offering anything new.
"This is a retreat back to the proposal of an Northern Ireland only backstop previously rejected by all sides in the House of Commons," he said.
Conservative MP, Steve Barclay, was also unimpressed with Barnier's comments. He said on Twitter: "With a very real deadline looming, now is not the time to rerun old arguments. The UK has put forward clear new proposals. We now need to agree a balanced solution that can work for both sides."
Barnier's comments come just three weeks before Britain is due to leave the EU, with a deeply split UK parliament yet to ratify Theresa May’s deal with Brussels last year on withdrawal terms and a separate declaration on the outlook for future trade relations.
The so-called “backstop” remains the big sticking point, a provision to keep the Irish border open in keeping with the 1998 Good Friday peace accord that ended sectarian conflict on the island of Ireland.
The eurosceptic wing of May’s Conservative party fears it could trap the UK in the EU’s trading rules forever.
Barnier said the bloc was ready to legally commit to using its “best endeavours” in trade negotiations with Britain after Brexit to find a solution that made sure the Irish border stayed open and the contentious backstop was never applied.