British Prime Minister Theresa May has said that an EU proposal for the Northern Ireland border threatens the constitutional integrity of the United Kingdom. <br />''<br />''A draft legal agreement published by the EU proposes a common regulatory area on the island of Ireland after Brexit, if solutions cannot be found. <br />''<br />''Ms May said, no UK Prime Minister could ever agree to this. The EU has said, the controversial backstop option is not intended to provoke the UK.<br />''<br />''Unveiling the draft agreement, EU Chief Negotiator Michel Barnier called on the UK to come up with alternatives. He said, the text is no surprise and is just a legally-worded assessment of what had been agreed so far.