The leader of the DUP Arlene Foster has said she will not accept any regulatory divergence between Northern Ireland and the rest of the UK after Brexit.
While she backed a "sensible Brexit", with a time limited transitional period and a deal to meet our financial obligations, she said her party would not stand for any move away from the rest of the UK.
In a brief statement, she said: "We will not accept any form of regulatory divergence which separates Northern Ireland economically or politically from the rest of the United Kingdom. The economic and constitutional integrity of the United Kingdom will not be compromised in any way"
Foster was speaking after reports surfaced that the UK and EU had agreed a joint agreement on the Irish border, in which the two sides of the island would maintain "regulatory alignment" - avoiding the need for a physical border to be deployed.
Foster said: "Her Majesty’s government understands the DUP position. The Prime Minister has told the House of Commons that there will be no border in the Irish Sea.The Prime Minister has been clear that the UK is leaving the European Union as a whole and the territorial and economic integrity of the United Kingdom will be protected."
This morning the PM's spokesman used that very phrase, saying the "territorial and economic integrity of the United Kingdom would be protected" after Brexit.
Foster concluded by saying the Republic of Ireland's government "are clearly seeking to unilaterally change the Belfast Agreement without our input or consent".
Update: This statement has been postponed. It is not clear exactly why, however Theresa May and Jean-Claude Juncker's lunch has overrun.
Foster is not the only politician to raise a red flag over the proposed solution.
SNP leader Nicola Sturgeon this afternoon tweeted: "If one part of UK can retain regulatory alignment with EU and effectively stay in the Single Market (which is the right solution for Northern Ireland) there is surely no good practical reason why others can’t."
First Minister of Wales Carwyn Jones agreed. "We cannot allow different parts of the UK to be more favourably treated than others," he said. "If one part of the UK is granted continued participation in the Single Market & Customs Union, then we fully expect to be made the same offer."
And London Mayor Sadiq Khan said: "Huge ramifications for London if Theresa May has conceded that it's possible for part of the UK to remain within the Single Market & customs union after Brexit. Londoners overwhelmingly voted to remain in the EU and a similar deal here could protect tens of thousands of jobs."
James McGrory, executive director of campaign group Open Britain, said: “One of the few things that generates agreement on Brexit is that it must not be allowed in any way to compromise the integrity of our United Kingdom. It appears today, however, to be doing just that...
“There is a solution that would solve all of these problems for the government, which is to keep the whole of the UK in the Single Market and the customs union. That would avoid a hard border in Ireland, ensure a level playing field for businesses across our islands, and protect trade with the EU, which buys almost half of everything we export.
“Anything else will damage our economy, put trade at risk, and widen divisions between the different nations of our country.”