Unionist leaders have laid out their objections to the proposed Brexit backstop during talks with the EU’s chief negotiator Michel Barnier.
DUP leader Arlene Foster has insisted any deal agreed as the UK prepares to leave the EU must meet her party’s red line.
Meanwhile, UUP leader Robin Swann told Mr Barnier that unionists in NI are “deeply concerned” at the proposed backstop plan and warned of the implications it could have for the Province’s place within the UK.
The government has promised to set out further proposals on the backstop arrangement aimed at avoiding a hard border on the island of Ireland, with speculation that it could involve regulatory checks on goods travelling between Great Britain and NI.
Last week, DUP MP Sammy Wilson told the News Letter that Theresa May would be “extremely foolish” to publish any new plans for the Irish border backstop without first running them past his party.
Speaking after her meeting with Mr Barnier in Brussels, Mrs Foster said her party needs to see the legal text of any agreement to check it against its red line, which rules out any extra barriers to trade between Northern Ireland and the rest of the UK.
The EU’s proposed backstop would see NI effectively remain in the customs union and single market while the rest of the UK shifts away from Brussels’ rules, something the prime minister has already said would be unacceptable.
Mrs Foster, whose 10 MPs play a critical role in propping up Theresa May’s government, said she wants to see a deal struck “that works for everyone”, while respecting the result of the referendum.
“It is vital that the EU understands the sensitivities surrounding Northern Ireland and that fact that we are going to be the only integral part of the UK with a land border with the EU after we leave next year,” she said.
“There cannot be barriers to trade in the UK internal market which would damage the economic well-being of Northern Ireland and therefore we could not support any arrangements which would give rise to either customs or regulatory barriers within the UK internal market.
“It’s been a useful meeting today, we look forward to continued engagement over the next couple of days.”
Following the meeting with the DUP delegation, Mr Barnier tweeted that his team is “working hard to explain and dedramatise the backstop”.
In a statement issued by the UUP, party leader Mr Swann said: “We made it clear to Michel Barnier that unionists in NI are deeply concerned by the proposed backstop and its implications for our place within the UK.
“The efforts to dedramatise do not go to the heart of unionist concerns and we underlined to Mr Barnier why the outworkings of the backstop are so problematic for us.”
Meanwhile, DUP Westminster leader Nigel Dodds said his MPs “would not tolerate” any separation of NI from the rest of the UK and threatened to withdraw support as they did last December.
He said: “The idea that the sort of proposals that are floating about from the EU side, and indeed some officials on our side in Brussels, are necessary to prevent a hard border on the island of Ireland is of course complete rubbish.
“There already is infrastructure on the border and there are already financial, fiscal and other differences because it’s an international border. Of course it can be managed.”