British MPs return to parliament on Wednesday following a momentous Supreme Court ruling that Prime Minister Boris Johnson's decision to suspend parliament was unlawful.

The judgement has dented Johnson's authority, prompting calls for his resignation and casting further doubt on his promise to pull Britain out of the EU on October 31, come what may.

The Conservative leader was due to arrive back from New York in the early hours, heading straight into a political maelstrom triggered by Tuesday's damning court ruling that his decision to suspend parliament for five weeks was unlawful.

The Speaker of the House of Commons, John Bercow, immediately announced that MPs would reconvene at 11.30 am (1030 GMT) on Wednesday, while the upper House of Lords said it would return later the same day.

Bercow said there would be no Prime Minister's Questions -- a weekly session held on Wednesdays -- but there would be "full scope for urgent questions, for ministerial statements, and for applications for emergency debates".

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The ruling throws his Brexit plans into disarray -- coming after a series of defeats in parliament that have curbed his plans for Brexit even if there is no divorce deal with Brussels.

Johnson told British media he "strongly disagreed" with the decision but said he would respect it.

The prime minister is likely to also renew his call for an early election to end the stand-off with parliament, having said in New York on Tuesday that it was "the obvious thing to do".

Despite the series of hammer blows in the House of Commons and the courts and losing his parliamentary majority, Johnson is still riding high in the polls and is keen for an election to try and win enough seats to allow him to carry out his plans to leave the EU.

But he requires the consent of opposition parties to hold a snap election and they are so far reluctant, preferring to use their working majority to keep a tight leash on Johnson as the Brexit deadline day of October 31 looms.

Labour has said it will agree to a vote once a no-deal Brexit has been ruled out, with a spokesman at its party conference saying on Tuesday that they will be taking "action tomorrow" regarding an election.

The 11 Supreme Court judges ruled on Tuesday that the parliamentary suspension, which came into effect this month, was "void and of no effect" because the prorogation was unlawful.

'Dead in a ditch'

Johnson had argued that shutting down parliament until October 14 was a routine move to allow his new government to set out a new legislative programme.

But critics accused him of trying to silence MPs.

Delivering the unanimous verdict, Supreme Court president Brenda Hale said "the decision to advise Her Majesty (Queen Elizabeth II) to prorogue was unlawful...because it had the effect of frustrating or preventing the ability of parliament to carry out its constitutional functions".

Jeremy Corbyn, the leader of the opposition Labour party, led calls for the prime minister to step down.

"I invite Boris Johnson... to consider his position, and become the shortest serving prime minister there has ever been," he told his party's annual conference.

But Johnson is likely to resist such demands, insisting that he must take Britain out of the EU next month whatever the circumstances.

In the week between returning from their summer holiday and prorogation on September 10, MPs passed a law aiming to stop "no deal".

The law obliges Johnson to ask to delay Brexit by three months if he has not agreed a divorce deal at an EU summit on October 17 and 18, but the prime minister has said he would rather "be dead in a ditch" than ask for another extension, setting up another potential showdown.

Johnson said Tuesday that he hoped to amend the divorce deal struck between the EU and his predecessor Theresa May, which has been rejected by MPs three times.

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British MPs return to Parliament
Boris Johnson's suspension of the British parliament never happened, the Supreme Court ruled. Photo: AFP / Tolga AKMEN