The defeat comes the day after MPs defied the government in a preparatory vote on the draft bill

British lawmakers inflicted a fresh defeat on Prime Minister Boris Johnson's Brexit strategy on Wednesday, approving in principle a law that could stop him taking Britain out of the European Union without a deal next month.

The House of Commons voted by 329 to 300 in favour of a draft bill that could delay Brexit for three months, although it still must pass further stages to become law.

Johnson had earlier warned he would call an early election on October 15 if the legislation went ahead, insisting Britain must leave the EU as planned on October 31, with or without a divorce deal with Brussels.

"I will never allow that," he told MPs about the delay plan, saying the draft law would "surrender" control over Brexit negotiations to Brussels.

But the government was braced for defeat, and has already introduced a motion for a vote later Wednesday calling for a snap poll before the last summit of EU leaders before Brexit, which begins on October 17.

In yet another twist in the tortuous Brexit process, however, the opposition Labour party is expected to withhold its support for the election, which requires the backing of two-thirds of MPs.

The defeat comes the day after MPs defied the government in a preparatory vote on the draft bill on Tuesday evening, when 21 of Johnson's own Conservative lawmakers rebelled.

He expelled them all, depriving his six-week-old government of a parliamentary majority.

'Sham' Negotiations

Johnson took office in July, three years after the 2016 referendum to leave the EU, promising to deliver Brexit whatever happens.

He says he wants to renegotiate the divorce deal struck with Brussels by his predecessor Theresa May, arguing that his threat of leaving with "no deal" will force EU leaders to agree better terms.

Brussels has so far refused, and the European Commission warned on Wednesday it saw no alternative to the current withdrawal agreement.

Labour leader Jeremy Corbyn said the idea that Johnson is negotiating with Brussels was "a sham -- all he's doing is running down the clock."

But Johnson insisted his team, which met with customs experts in Brussels on Wednesday, was making "substantial progress".

The EU Commission also said the risk of a "no deal" exit has increased, a prospect many fear because of the economic damage it could cause after almost half a century of close ties with Britain's closest neighbours.

However, Bank of England governor Mark Carney said Wednesday the institution believed the impact would be "less severe" than previously forecast, in part because of government preparations.

Labour 'Not Dancing'

On Tuesday night, rebel Tories joined with Labour and other opposition MPs to clear the Commons timetable on Wednesday afternoon to debate their own Brexit legislation.

Their bill would force the government to delay Brexit until January 31 unless it has agreed exit terms with the EU at a summit on October 17-18, or secured MPs' approval for a "no deal" divorce.

But it also raises the prospect of rolling Brexit delays, and Johnson warned it would only cause "more confusion" and wreck any hopes of a deal.

It must be approved by MPs and the unelected House of Lords before Monday to take effect.

Johnson earlier challenged Labour to back his call for an election, urging Corbyn to "let the people decide" how to resolve the Brexit impasse.

However, the party is expected to abstain amid fears Johnson might reschedule the poll until after October 31 to make sure that Britain leaves the bloc, with or without a deal.

"Nobody believes him because the levels of trust in Boris Johnson are very, very low," Labour's Brexit spokesman Keir Starmer told ITV.

"So we're not going to be voting with Johnson today. We want a general election, but we're not dancing to his tune."

Johnson has received a poll boost for his tough talk on Brexit, but an election could also be a risk, as the Conservatives are threatened by the eurosceptic Brexit Party.

There was some respite for the government on Wednesday when a court in Scotland ruled that Johnson's decision to suspend parliament for over a month starting next week was lawful.

The 75 parliamentarians behind the legal challenge accused the prime minister of curbing opposition attempts to block his Brexit strategy and bring down his government.

A similar case will be heard in London on Thursday.