After failing to get parliament's approval three times for Prime Minister Theresa May's Brexit deal, the government will now put the bill, legislation which will enact that deal, before parliament for a vote in early June.

"I want to make it clear that Labour opposes the idea of passing the Withdrawal Agreement Bill without an agreed deal ... and Labour will vote against a second reading on that basis," Starmer told parliament.

Starmer's comments come as Brexit-supporting rebels in May's Conservative Party said they'd vote down her EU divorce deal when she brings it back to parliament next month.

The United Kingdom is now scheduled to leave, with or without a deal to smooth the exit, by October 31.

Defeat in the vote would likely spell the end of May's divorce deal and probably her premiership.

May will bring a Withdrawal Agreement Bill, which implements the departure terms, to parliament for a vote in the week beginning June 3, Brexit Secretary Steven Barclay said.

The vote is due just as US President Donald Trump begins a divisive state visit to Britain.

Conservative MP and Brexit supporter Peter Bone thought the deal had little chance of being passed.

"I have talked to colleagues, some of whom voted for it last time, and they think it is dead and they will vote against it this time," he told Talk Radio on Wednesday.

"It seems absurd to bring it back. It is the same thing again, again and again."

May, who became prime minister in the chaos that followed the 2016 referendum in which Britons voted 52 per cent to 48 per cent to leave the EU, is under pressure from some of her own MPs to set a date for her departure.

As well as the Brexit deadlock, the Conservative Party suffered major losses in local elections this month and is trailing in opinion polls ahead of the May 23 European Parliament elections.

May's spokesman declined to say on Wednesday whether the prime minister would resign if she failed again to win parliamentary support for her Brexit deal.

Australian Associated Press