Video report by ITV News Political Correspondent Paul Brand
Boris Johnson insists the UK will leave the European Union on October 31 with "no delay".
In a tweet posted after a court was told the prime minister would ask for an extension, he said: "New deal or no deal - but no delay."
His short message came after documents disclosed in court revealed his Government will ask for a Brexit delay if he fails to get a deal with Brussels despite his “do or die” promise to get the UK out of the European Union on October 31.
The Prime Minister accepts the terms of the Benn Act, which requires him to seek an extension if a deal has not been agreed with the EU by October 19, according to a submission to Scotland’s highest court.
ITV News Political Correspondent Paul Brand says the PM is making the countdown to Brexit as big a struggle as possible with an eye on a General Election
Downing Street refused to comment after the documents were read out during the case at the Court of Session.
The Prime Minister has publicly said “we will obey the law, and will come out on October 31” in any event, without specifying how he would achieve the apparently contradictory goals – fuelling speculation that he had identified a loophole to get around the Benn Act.
It later emerged that European Union member states have agreed that the Government's new Brexit proposals "do not provide a basis for concluding an agreement", a European Commission spokesman said.
The spokesman said it would meet again on Monday to give the UK "another opportunity to present its proposals in detail".
But, the spokesman said, the current proposals did not go far enough to provide the basis for a deal.
The legal action – led by businessman Vince Dale, SNP MP Joanna Cherry QC and Jolyon Maugham QC – is asking the court to require Mr Johnson to seek an extension to avoid leaving the EU without a deal.
Mr Maugham told Sky News: “What we learned today is that the Prime Minister has promised the court, in his own name, that he will ask for an extension under the Benn Act if the conditions are satisfied, in other words if Parliament has not before October 19 agreed a withdrawal agreement.
“He’s also promised the court that he will not frustrate the Benn Act by which is meant that he will not send two letters, one saying ‘can I have an extension’, the other saying ‘please don’t give me one’, he won’t collude with foreign governments to attempt to persuade those foreign governments to veto an extension.”
The Irish premier said Ireland would likely agree to a request by the UK for a Brexit extension.
Speaking in Denmark, moments after the court documents were revealed, Leo Varadkar said if Boris Johnson submits a request for an extension, he would agree.
“I’ve always said that Brexit doesn’t end with the UK leaving, it’s just the next phase of negotiations, but if the UK were to request and extension, we would consider it, most EU countries would only consider it for good reason, but an extension would be better than no deal,” he said.
Mr Varadkar was speaking alongside the Danish prime minister Mette Frederiksen, who also agreed to a Brexit extension, before he added that he still believes a deal is possible at the EU Council Summit in mid-October.
“Our focus is on securing an agreement and getting a deal at the EU Council Summit,” the Taoiseach added.
“I believe that’s possible but in order for it to be possible all sides have to reaffirm the shared objectives, when this started two or three years ago, coming to an agreement required no hard border between Ireland, north and south, that the integrity of the Single Market of the European Union will be protected, and that the all-island economy will be protected.
“What we need to do is refocus on those objectives and come to an agreement by the middle of October, and I think that is possible.”
Simon Coveney gives an update on Ireland's Brexit position
Meanwhile, Ireland's deputy premier Simon Coveney, who on Friday afternoon held talks with Northern Ireland Secretary Julian Smith in Hillsborough, Co Down, said he was not giving up on the chance of getting a Brexit deal in October.
Reiterating earlier comments from the Taoiseach, Mr Coveney said if an agreement was not possible this month, then Ireland would prefer an extension to a no-deal exit.
"I believe it is possible to get a deal this month," he said.
"I believe that the British Prime Minister wants to get a deal this month. We will certainly work to that time frame if the British position evolves and we want to be helpful on that.
"I don't think we should give up on that.
"If it's not possible Ireland has always said we would prefer an extension to no deal.
"But that's the Irish position but I don't speak for lots of other EU member states."
DUP leader Arlene Foster also had talks with Mr Smith but insisted the talks focused on restoring powersharing, not Brexit.
"We were focused very much on devolution and the return of devolution; we were not discussing Brexit," she said.
"Because I think the people of Northern Ireland have waited a long time to have their devolved government up and running again.
"We have dealt with Brexit-related issues earlier in the week. There's been a reasonable and sensible proposal put forward, those now have to go through the process with the European Union.
"We are focused very much on trying to get devolved government back and I hope the other parties are as well."
The Prime Minister is expected to embark on a tour of European capitals for face-to-face talks next week as well as continuing to speak by phone to counterparts.
European Commission spokeswoman Natasha Bertaud said: "What we have always said is that every day counts, especially as we near the end of October."
The Prime Minister's Europe adviser, David Frost, has been in Brussels for technical talks with officials.
Downing Street also indicated the Government would consider publishing the full legal text of Mr Johnson's proposals, which have so far only been shared confidentially with Brussels.