Leaks from Dublin today suggest the UK is set to concede there will be no “divergence” on single market and customs unions rules on the island of Ireland. 

A draft of the proposals to be sent to the EU will concede Northern Ireland will be “aligned” to the Republic - not to the UK. 

Ms Foster responded to these proposals furiously this lunchtime, declaring the party would not stand for "any form of regulatory divergence" on the island. 

She claimed Dublin was attempting to “unilaterally change” the terms of the Good Friday Agreement - despite the fact the DUP was the only major Northern Irish party to campaign against the agreement. 

Ms Foster said: “We note the speculation emanating from the European Union exit talks regarding the Republic of Ireland and United Kingdom border.

"We have been very clear. Northern Ireland must leave the EU on the same terms as the rest of the United Kingdom. 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.

“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.

“We want to see a sensible Brexit where the Common Travel Area is continued, we meet our financial obligations, have a strictly time limited implementation period and where the contribution of EU migrants to our economy is recognised in a practical manner. 

“The Republic of Ireland claim to be guarantors of the Belfast Agreement but they are clearly seeking to unilaterally change the Belfast Agreement without our input or consent.”

The DUP had previously threatened to withdraw their support for Theresa May’s government, which is being held up by their 10 MPs, if they cave in to EU demands. 

Downing Street, however, said they believed the DUP would support the deal by the end of play today. 

The DUP has repeatedly demanded no special treatment for Northern Ireland - despite the majority of people in the country voting Remain and an even higher percentage opposing leaving the customs union and single market.

The Democratic Unionist Party (DUP) has warned Theresa May that the idea of using the Irish Sea as a post-Brexit border between the rest of the UK is 'non-negotiable'.

Nigel Dodds, who leads the DUP in Westminster, said any proposals to make special arrangements for Northern Ireland in Brexit talks should be firmly off the table.

Yesterday speaking to Jon Pienaar said the Irish government's agressive stance on Brexit has "caused real damage to Anglo-Irish relations... they can't impose what is a good solution for the Irish Republic on the rest of us."

Speaking at the DUP's annual conference last week in Belfast, Mr Dodds said:  'Make no mistake - for us the integrity of the United Kingdom is non-negotiable.

The DUP declined to comment when contacted by Express.co.uk.

The leader of unionist party TUV, formed after a split from the DUP in 2007, said the situation was “lunacy”.

Jim Allister said: “If this turns out to be correct then the clear inference is that there would be regulatory divergence with Great Britain. 

“Northern Ireland is being cut adrift from the rest of the United Kingdom.

“I think this is a stepping stone to a United Ireland.

“The thing is lunacy. Any so-called unionist Prime Minister who presided over this is a Prime Miniter who should be removed from office.”

And the DUP’s Sammy Wilson said the proposal would have been vetoed at Northern Ireland’s Stormomt government - which is currently not sitting due to a break down in talks with Sinn Fein. 

Northern Ireland’s legislative body collapsed over the DUP’s red line issues: primarily their opposition to gay marriage and extra Irish language funding. 

RTE's Europe editor Tony Connelly tweeted: “BREAKING: UK will concede that there will be no ‘regulatory divergence’ on the island of Ireland on the single market and customs union, acc to a draft text seen by RTE News.

“According to one version of the EU-UK draft: ‘In the absence of agreed solutions the UK will ensure that there continues to be no divergence from those rules of the internal market + customs union which, now or in the future, support North South cooperation +protection of the GFA.’

“The draft text on Ireland has since been updated to include the phrase 'continued regulatory alignment' rather than ‘no regulatory divergence’, according to well-placed sources.