Boris Johnson’s battle to get his last-minute Brexit deal approved by MPs intensified when the DUP ruled out backing the agreement.

Following days of intense negotiations, the Prime Minister announced he had struck a “great new deal” with Brussels as he headed to a summit of EU leaders on Thursday.

But it must still be passed by Parliament and Mr Johnson’s key ally, the DUP, was standing firm over its objections to his agreement and insisted it would not get their backing.

A statement from Arlene Foster’s party, which has been in close and regular talks with the PM, criticised his effort for undermining the integrity of the union and being bad for Northern Ireland’s economy.

The deal also “drives a coach and horses” through the Good Friday peace agreement over the issue of consent.

“Following confirmation from the Prime Minister that he believes he has secured a ‘great new deal’ with the European Union the Democratic Unionist Party will be unable to support these proposals in Parliament,” the DUP said.

MPs are expected to hold a meaningful debate on the deal in the House of Commons on Saturday, the first weekend sitting of Parliament in 37 years.

If Parliament does not back his deal by Saturday, Mr Johnson faces an almighty clash over whether he will request a further Brexit delay from Brussels as he is compelled to under the Benn Act.

Mr Johnson was due to meet European Commission president Jean-Claude Juncker after he arrives at the two-day summit in Brussels on Thursday afternoon.

The stance of the DUP is particularly important because the party wields influence over some hardline Tory Brexiteers and Mr Johnson is far short of a majority in Parliament.

Announcing his achievement, the PM tweeted: “We’ve got a great new deal that takes back control, now Parliament should get Brexit done on Saturday so we can move on to other priorities like the cost of living, the NHS, violent crime and our environment.”

He insisted the deal allows the UK to leave the bloc “in two weeks”, just in the nick of time to satisfy his “do or die” commitment to leaving by the current October 31 deadline.

Mr Johnson said that the “anti-democratic” backstop contingency measure to prevent a hard border on the island of Ireland had been abolished.

It proved a major sticking point for his predecessor Theresa May whose deal failed to pass the Commons three times.

“The people of Northern Ireland will be in charge of the laws that they live by, and, unlike the backstop, will have the right to end the special arrangement if they so choose,” the PM added.

But the DUP dug in over the prospect of a customs border between Northern Ireland and the rest of the UK, as well as the issues of consent regarding the suspended Stormont Assembly.

Another issue in the PM’s proposals was whether EU VAT rates would apply in Northern Ireland.

Mr Johnson needs to get a deal approved before the weekend if he is to avoid a major clash over asking for an extension to the current October 31 deadline.

The Benn Act passed by no-deal opponents compels him to ask Brussels for a delay to the end of January, but the PM has repeatedly ruled out taking this course of action.

European Commission president Jean-Claude Juncker said it represents a “fair and balanced agreement” for both the EU and the UK, as he compelled European leaders to back the deal.

Jeremy Corbyn was quick to dismiss the PM’s agreement, criticising it for creating a customs border in the Irish sea.

“As it stands we cannot support this deal,” the Labour leader told reporters in Brussels, adding that it did not seem to have the backing of “many of his allies on his own backbenches”.

Mr Corbyn criticised “high-level speculation” when asked about reports that his party could support the deal if it comes with a second referendum.

Nicola Sturgeon also ruled out her MPs in the SNP backing the deal, insisting it will mean Scotland alone is “treated unfairly” when the UK leaves the European Union.

EU chief negotiator Michel Barnier told a press conference that discussions “have at times been difficult” but that they had “delivered together”.

“There should be no surprises here, much of the final text can also be found in the agreement that was put forward a year ago,” he said.

“There are some new elements including on Ireland and Northern Ireland.

“This agreement has been built together with the UK, that’s why I am confident it can be supported and ratified in time.”

But the PM’s chances of ending the Parliamentary deadlock were seriously in doubt over the sticking points highlighted by the key Tory allies in the DUP.

This is despite the PM having been in close and continued contact with Ms Foster and her deputy Nigel Dodds as he tried to shore up their support ahead of Saturday’s key deadline to prevent a delay to Brexit.

The PM’s spokesman said Mr Johnson plans to hold a meaningful vote on the Withdrawal Agreement and the Political Declaration on Saturday if MPs on Thursday back proposals for Parliament to sit on the weekend.