A number of senior Conservatives haves urged the British Prime Minister not to appeal against a High Court ruling which states that Parliament must vote on leaving the European Union.

Oliver Letwin, the former head of the government's Brexit preparations, has called for Theresa May to abandon the Supreme Court appeal over the decision on Article 50, the mechanism that triggers exit negotiations.

Ex-attorney general Dominic Grieve and former solicitor-general Edward Garnier also said Ms May should avoid the highest court in the UK.

The Conservatives, who all supported the Remain campaign, instead want the process commenced as soon as possible with a Bill in Parliament.

Mr Garnier told the BBC Radio 4 Today programme: "That way you avoid an unnecessary legal row, you avoid a lot of unnecessary expense, but you also avoid an opportunity for ill-motivated people to attack the judiciary, to misconstrue the motives of both parties to the lawsuit, and you provide certainty."

Mr Letwin, a former minister who was director of the "Brexit Unit" following the referendum, said avoiding the Supreme Court would avert a risk of judges granting "veto powers" to devolved administrations.

Mr Grieve told Today that the government's chance of success at the Supreme Court hearing, scheduled to start on 5 December, is low.

He added: "I can't see the point in the government continuing with the case and also agree that if they enact primary legislation, they will get it through Parliament."

Three High Court judges ruled on 3 November that Ms May does not have the power to trigger Article 50 alone.

The government quickly announced that it would appeal against the decision.

A spokesman for the Department for the Exit of the European Union said: "The country voted to leave the European Union in a referendum approved by an Act of Parliament and the government is determined to respect that result.

"We will robustly defend our position in the forthcoming appeal. As the Prime Minister made clear (on Friday), our work is on track and we remain committed to triggering Article 50 by the end of March next year."