Reaction was swift Tuesday night to British Prime Minister Theresa May's final bid to persuade Westminster politicians to back her under-fire Brexit deal.

May's plan, rejected three times already by MPs, has been rebranded with a list of goodies in the hope she will finally strike it lucky.

In a keynote speech in London, May unwrapped a 10-point plan, backed by her senior ministers, saying it gave MPs one last chance to deliver Brexit.

Politicians will be offered a vote on whether to hold another referendum if they back the government's Withdrawal Agreement Bill, said May.

But, if as widely predicted, MPs again reject the bill, a negotiated exit from the EU would be dead in the water and Brexit could be stopped, warned May, whose days as Britain's prime minister are already certain to be numbered.

Describing it as finding common ground in Parliament, May said her plan was the only way to deliver the Brexit the people of Britain voted for in 2016.

Leading Conservative Brexiteer MP Charlie Elphicke said the deal would prevent Britain from agreeing trade deals with the fastest growing economies in the world.

In what was a curtain raiser to the response of the main opposition Labour Party, its leader Jeremy Corbyn on Tuesday night described May's bill as effectively repackaging of same old bad deal.

In his first reaction to May's speech, Corbyn said: "The prime minister's proposal tonight seems to be largely a rehash of the government's position in the cross party talks that failed to reach a compromise last week."

Corbyn said his party will look seriously at the details of the withdrawal agreement bill when it is published in several days.

"But we won't back a repackaged version of the same old deal, and it's clear that this weak and disintegrating government is unable deliver on its own commitments," said Corbyn.

Labour veteran politician, Dame Margaret Beckett was even more scathing, saying: "May's deal has no chance."

"It would be very dangerous to vote through a deal to leave the EU without any clear idea of our eventual destination, a blindfold Brexit that would only prolong uncertainty for families, businesses and Parliament," she said.

Leave-supporting Jacob Rees-Mogg, chairman of a group of Conservative MPs who want Britain to leave the EU, told the Daily Telegraph: "I wouldn't put money on my backing the deal."

Scotland's first minister Nicola Sturgeon, said on her social media site: "The PM is asking MPs to vote for a bill that takes us out of the EU - in Scotland's case against our will - out of the single market and possibly out of the Customs Union, and with no actual commitment to put the deal to a second referendum."

Nigel Dodds, leader of the Democratic Unionist Party (DUP) MPs at Westminster said the fundamental flaws of the draft Withdrawal Agreement treaty remain unchanged.

The DUP has a supply and confidence agreement with the governing Conservatives to give May's minority government a majority in the House of Commons.