British Prime Minister Theresa May has said MPs faced a choice ahead of a vote on her Brexit deal: approving her deal or facing an exit with no deal or even the reversal of Brexit.

She said she was speaking to MPs about giving parliament a bigger role in whether the Irish backstop arrangement would be triggered, though she gave few details.

Mrs May said some in parliament were trying to frustrate Brexit and that she did not think another referendum on Brexit was the right course.

Speaking on BBC’s Radio 4 she said: "There are three options: one is to leave the European Union with a deal... the other two are that we leave without a deal or that we have no Brexit at all."

She added: "It's clear that there are those in the House of Commons who want to frustrate Brexit ... and overturn the vote of the British people and that's not right."

Mrs May repeatedly sidestepped questions on whether she would delay the 11 December vote, but did hint at possible concessions on the backstop.

"There are questions about how decisions are taken as to whether we go into the backstop, because that isn’t an automatic," she said.

"The question is: do we go into the backstop? Do we extend what I call the implementation period?"

When asked repeatedly what her "Plan B" would be if her deal was rejected, she did not directly answer the questions.

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Earlier, the DUP insisted it would withdraw support for Mrs May's government if she pressed ahead with her Brexit deal with the EU.

Asked if the DUP was prepared to precipitate a general election, the party's Brexit spokesman Sammy Wilson told the same programme: "If it comes to the point where the government makes, shows, a determination to implement the Withdrawal Agreement with its damaging terms at present, or some future version of it, which is still equally damaging, we will not be supporting the government."

Referring to the DUP's agreement to prop up the Tories in the Commons, Mr Wilson added: "If they break the agreement which they have with us, then they don't have our support.

"If they renege on those promises now, or in the future, we always have that leverage."

Labour has indicated it will table a motion of no confidence in the prime minister in the wake of a defeat on such a pivotal issue for Mrs May.

Meanwhile, the European Court of Justice will deliver its judgment on whether Britain can unilaterally reverse its move to leave the European Union on Monday 10 December at 8am, the court said.

An ECJ adviser issued an opinion in the case on Tuesday that Britain could simply stop Brexit without seeking approval from other member states.

The judges usually follow such opinions.

Additional Reporting PA