Britain’s parliament last night defeated Prime Minister Theresa May’s Brexit deal by a massive margin, triggering a no-confidence vote that could bring down her government, said media reports.

The House of Commons lower house voted 432 to 202 against May’s plan for taking Britain out of the European Union after nearly five decades, one of the biggest defeats ever suffered by a British premier.

The EU warned that the vote, which plunges Britain into uncharted waters, boosts the risk of a “no deal” Brexit.

Moments after the big defeat, opposition Labour leader Jeremy Corbyn submitted a motion of no-confidence in May’s government to trigger a general election.

However, one senior party figure has suggested it is unlikely to succeed, with Northern Ireland's DUP and Tory rebels saying they will back the PM, reported BBC.

The confidence vote is expected to be held at about 19:00 GMT, it stated.

May has told MPs she will return to the Commons with an alternative plan next week, provided she survives the confidence vote.

"The House has spoken and this government will listen," she said on Tuesday night, offering cross-party talks to determine a way forward.

Speaking moments before the MPs cast their ballots, May said MPs had a “duty to deliver” on the results of a 2016 referendum that started the divorce.

“I believe we have a duty to deliver on the democratic decision of the British people,” May said, warning MPs that the EU would not offer any “alternative deal”.

“A vote against this deal is a vote for uncertainty, division, and the very real threat of a no deal,” she argued to jeers from the packed chamber.