Boris Johnson goes down in epic flames as British MPs defeat him on Brexit

Prime Minister Boris Johnson suffered a major parliamentary defeat over his Brexit strategy on Tuesday, which could delay Britain's exit from the European Union next month and force an early election.

Just six weeks after taking office, the Conservative leader was hit by a huge rebellion among his own MPs that leaves him without a working majority in the House of Commons.

They joined with opposition MPs to begin the process of drafting legislation intended to stop Johnson taking Britain out of the EU on October 31 if he has not agreed a deal with Brussels.

The prime minister had warned that anyone who voted against him would be expelled from the party.

He is now expected to table a motion for an early election before parliament on Wednesday, with the poll date expected before a crucial EU summit on October 17 and 18.

However, it is not certain he will succeed as it requires the support of two-thirds of MPs -- and the opposition Labour party is deeply distrustful of Johnson's motives.

The former London mayor took over as premier in July promising to finally deliver on the 2016 referendum vote for Brexit, after his predecessor Theresa May delayed exit day twice.

Johnson says he wants to agree a divorce deal with Brussels, but says if this is not possible, Britain should leave the EU next month regardless.

However, there are not yet any formal negotiations with the EU and MPs are increasingly fearful of a disorderly divorce, which they believe could cause significant economic damage.

The heightened political tension sent the British pound tumbling on Tuesday to its lowest level against the dollar in almost three years.

It also spilled out onto the streets outside parliament, where anti-Brexit protesters gathered.

"Coming out of the EU with no deal at all is the worst possible option," said John Wetherall, a retired chemical engineer carrying EU flags.

- 'Last opportunity' -

In a heated debate before the vote, Johnson condemned attempts to tie his hands as "surrender", saying the rebels' plan would hand power over exit negotiations to Brussels.

But his critics won an early boost by the dramatic defection of Conservative MP Phillip Lee, who crossed the Commons while Johnson was speaking to sit with the pro-European Liberal Democrats.

Lee said in his resignation letter that the Conservative party "has become infected with the twin diseases of populism and English nationalism" as a result of Brexit.

Tuesday's vote will clear time in the House of Commons on Wednesday to introduce legislation that could force Johnson to delay Brexit to January 31 if he cannot agree an EU deal by October 19.

MPs are racing to get it through before parliament is suspended next week, in what Labour leader Jeremy Corbyn said "may be our last opportunity" to prevent a chaotic Brexit.

But government minister Jacob Rees-Mogg said the move sought to "confound the referendum result" after Britons voted for Brexit in 2016.

Lee's defection means the prime minister no longer has a majority in the 650-seat chamber -- and if the rebels are expelled, Johnson's position will be further weakened.

But he remains in government until he loses a formal confidence vote, or calls an election.

On a day of high drama, an Edinburgh court also heard a legal challenge against Johnson's decision to suspend parliament next week for more than a month. Critics said Johnson's move was a bid to silence MPs.

The judge is expected to announce his ruling on Wednesday.

Johnson insists his threat to leave the EU without a deal will ultimately force the bloc to sign up to new terms to ease the end of Britain's 46-year membership of the bloc.

But his critics warn this is wishful thinking.

In the meantime, leaked government assessments have warned that no-deal could lead to food, fuel and medicine shortages.

UN economists also on Tuesday warned that Britain could lose at least $16 billion (14.6 billion euros) a year on exports to the European Union if it left without a deal.

If Johnson's bid for an election fails, or if the "no deal" legislation fails, Corbyn has warned he might still try to stop the prime minister by calling a confidence vote in the government.