Brexit: EU negotiator to meet Sinn Féin and DUP
Michel Barnier is to meet the DUP leader Arlene Foster and Sinn Féin deputy leader Michele O'Neill on Monday.
The meeting comes as the EU negotiator unveiled a draft Brexit agreement on Wednesday morning.
The document proposes a "common regulatory area" on the island of Ireland if solutions cannot be found for the post-Brexit border.
She said that it threatens the "constitutional integrity" of the United Kingdom.
- A Brexit warning from one prime minister to another
- Johnson says NI border row being exploited
- Brexit: All you need to know
Unionist politicians have strongly rejected the idea but the Taoiseach (Irish prime minister) Leo Varardkar said it was now up to proponents of Brexit to come up with solutions to ensure that there is no hard border between Northern Ireland and the Republic of Ireland after the UK leaves the EU.
The DUP leader Arlene Foster tweeted that the draft text was "constitutionally unacceptable and would be economically catastrophic for Northern Ireland".
The Ulster Unionist leader Robin Swan said the draft proposal was "a complete non-starter for Unionists".
He described the draft agreement as "nothing short of a move by the EU to annex Northern Ireland".
"No British Government could accept this.
"It demonstrates complete and utter contempt for Northern Ireland's constitutional position and also for the Belfast Agreement," he added.
The TUV leader Jim Allister said the draft treaty "seeks to subvert the integrity of the United Kingdom by demanding that Northern Ireland is hived off under EU jurisdiction into its customs union, which, of necessity then requires border checks between Northern Ireland and Great Britain".
However the SDLP Brexit spokesperson Claire Hanna said her party "welcomes the EU's cast iron commitment to protecting the Good Friday Agreement and preventing a border in Ireland".
"Despite some utterances on the airwaves from some, there is nothing surprising in this draft withdrawal agreement today - this is essentially what was agreed by the UK and the EU in December.
"The UK Government and the Brexiteers have a choice, they either go for alignment with the Customs Union and the Single Market to protect these islands - or they support the EU on the common regulatory area," she added.
Speaking in the Irish parliament Sinn Féin president Mary Lou McDonald welcomed the draft proposal which she said recognises that Northern Ireland must stay in the customs union post-Brexit.
She accused the British government and Brexiteers of debating Brexit "with zero regard for the impact on Ireland".
"And now," she said, "they want to conclude their debate, and make their exit by putting the Good Friday Agreement through the shedder.
"The Tory-DUP axis is satisfied to treat the welfare of the people of this island as collateral damage so long as they can achieve their 'little Englander' Brexit," she added.
She called on the Taoiseach Leo Varadkar to convene the British-Irish Intergovernmental Conference.
In reply to Ms McDonald, Taoiseach Leo Varardkar said that the UK government had made a commitment that there would be no border between the Republic and Northern Ireland.
"This is the last resort as Prime Minister May describes it, there are alternative solutions," he said.
He said his government and the UK government shared the preferred option of avoiding a hard border in Ireland as well as between the island of Ireland and Great Britain.
"I do not want a border between Letterkenny and Derry any more than I want a border between Larne and Stranraer."
He said that it was now up to "hard-line Brexiteers" and some politicians in Northern Ireland to come up with alternatives saying "just saying no and being angry isn't enough".
"It is up to them now to come up with alternative solutions... in a legal form that can be enforced."