Jeremy Corbyn has said Labour would offer a “sensible” Leave deal in a new Brexit referendum as he signalled he could remain neutral in such a vote.

The comments come just days before Labour’s annual party conference where Mr Corbyn is expected to come under heavy pressure to take a stronger pro-Remain stance.

Brexit continued to dominate politics as Prime Minister Boris Johnson was defending his highly controversial move to suspend Parliament for five weeks as the October 31 EU withdrawal deadline approaches.

Lawyers representing the PM at the Supreme Court were set to argue on Wednesday that his advice to the Queen to prorogue Parliament was lawful and that, in any event, the court cannot interfere in political matters.

The Government is facing a legal challenge from critics who claim that Mr Johnson’s decision to suspend Parliament was intended to prevent scrutiny of his Brexit stance.

Mr Corbyn said Labour would negotiate a new Leave agreement with the EU if it wins the next general election and then put that to a vote along with a Remain option.

Writing in The Guardian, Mr Corbyn said: “A Labour government would secure a sensible deal based on the terms we have long advocated, including a new customs union with the EU; a close single market relationship; and guarantees of workers’ rights and environmental protections.

“We would then put that to a public vote against remain, and I pledge to carry out whatever the people decide, as a Labour Prime Minister.

“We are the only UK-wide party ready to put our trust in the people of Britain to make the decision.

“(Boris) Johnson wants to crash out with no deal. That is something opposed by business, industry, the trade unions and most of the public – and even by the Vote Leave campaign’s co-convener, Michael Gove, who said earlier this year: ‘We didn’t vote to leave without a deal.’

“And now the Liberal Democrats want MPs to overturn the referendum result by revoking article 50 in a parliamentary stitch-up.

“It is simply undemocratic to override the decision of a majority of the voters without going back to the people.”

The comments appeared to signal that Mr Corbyn could adopt a neutral position in any future referendum if he became PM.

Emily Thornberry (Sophie Hogan/PA)

A number of senior shadow cabinet figures, such as Emily Thornberry and John McDonnell, have said they would back Remain in a new referendum.

Labour’s deputy leader Tom Watson has gone further by calling for another national poll on Brexit before any general election is held.

Conservative Party chairman James Cleverly said: “Jeremy Corbyn and the Labour Party want to ignore the largest democratic vote in our country’s history and cancel the referendum result.

“They had the chance to let the public decide how to resolve Brexit via a general election – but Jeremy Corbyn doesn’t trust the people.”

The remarks came as the Daily Telegraph reported that the US ambassador to Britain, Woody Johnson, had expressed support for the way Mr Johnson handled a visit to Luxembourg where he declined to hold an outdoor news conference with the country’s premier Xavier Bettel in case it was overshadowed by the chants of anti-Brexit campaigners.

The newspaper said Woody Johnson told a meeting at the Carlton Club in London the Prime Minister “knew he was walking into a trap”:

“He knew this was a set-up.

“Of course he knew, but he’s British. He said, ‘What the hell. I can do this’.

“I thought the people in Luxembourg accomplished something that maybe even Boris couldn’t accomplish: show this is not where (the British) want to be, over there, when they treat us like that – your Prime Minister.”

The Supreme Court in London is hearing historic appeals from two separate challenges brought in England and Scotland concerning the prorogation of Parliament.

Mr Johnson says the five-week suspension is to allow the Government to set out a new legislative agenda in a Queen’s Speech when MPs return to Parliament on October 14.

The court, which is sitting as a panel of 11 justices for only the second time in its 10-year history, must reconcile contradictory judgements issued by the English and Scottish courts.

The High Court in London dismissed the case brought by businesswoman and campaigner Gina Miller, finding that the length of the prorogation was “purely political”.

But the Inner House of the Court of Session in Edinburgh ruled that Mr Johnson’s decision was unlawful because “it was motivated by the improper purpose of stymying Parliament”.