Boris Johnson has staked his leadership on a promise to get Brexit done at any cost next month (AFP)

British Prime Minister Boris Johnson raised the stakes Monday in a pivotal week of the Brexit saga by threatening to purge ruling party lawmakers who try to block a no-deal divorce with the EU.

The warning came as heavyweights from the governing Conservatives such as former finance minister Philip Hammond plotted a way to keep the premier from taking Britain out of the European Union on October 31 without an agreement.

Johnson insists he must keep the chaotic option open to try to persuade Brussels to relent at the last moment and agree a better economic deal for Britain.

He poured more oil on the political fire by deciding last week to suspend parliament -- a legal but highly contentious manoeuvre -- for more than a month.

As a result, pro-European lawmakers will have just days to try to tie Johnson's hands and avoid a painful split from Brussels when they return from their summer break on Tuesday.

"It would be entirely unreasonable for MPs, having rejected the previous deal three times, to attempt to bind the hands of the PM as he seeks to negotiate a deal they can support," the prime minister's spokesman told reporters.

A Downing Street source told AFP that Johnson will be meeting his cabinet later on Monday.

"Last chance"

Johnson has upturned political traditions and inflamed passions on both sides of the Brexit chasm since taking over from Theresa May in July.

His strategy of counter-punching his domestic opponents and playing a game of chicken with Brussels has helped his flagging party to shoot back up to the top of opinion polls.

But he enjoys a majority of just one in parliament -- a margin that has prompted many to assume that he wants Brexit to happen by any means possible and then to hold a general election.

"Tomorrow's possible vote is an expression of confidence in the government's negotiating position to secure a deal and will be treated as such," the Downing Street source said.

Trying to stop Johnson will be tricky for MPs like Hammond and pro-European lawmakers from opposition parties who each have their own political interests in mind.

Their first step on Tuesday will see them try to seize power from the government over what legislation is put up for a vote.

Success would then see them draft -- and pass -- legislation by next week that obliges Johnson to secure a Brexit extension at an October 17-18 EU summit.

Almost two dozen moderate Conservatives have backed similar attempts in the past.

They will be relying on support of the main opposition Labour Party and pro-EU lawmakers from the Scottish National Party and the resurgent Liberal Democrats.

"We must come together to stop no-deal," Labour leader Jeremy Corbyn told his supporters outside the northern city of Manchester.

"This week could be our last chance."

Secret report

Johnson has staked his leadership on a promise to get Brexit -- already delayed twice due to parliamentary resistence -- done at any cost next month.

His government unfurled a formal "get ready for Brexit" campaign Monday that included a website advising EU and UK nationals on how to deal with potential problems such as their phones not working abroad.

Both Brussels and London now view a no-deal end to the four-decade partnership as the most likely outcome.

EU negotiator Michel Barnier wrote in The Sunday Telegraph that the current agreement's most contentious element -- a so-called backstop to keep the Northern Irish border open in all post-Brexit circumstances -- was "the maximum amount of flexibility that the EU can offer".

Johnson's insistence that there were other solutions -- including one involving high-tech border technology -- was punctured further by the leak of a UK government report showing that none of them worked.

"It is evident that every facilitation has concerns and issues related to them," The Guardian quoted the August 28 dossier as saying.

The report added that its findings should be kept private "given (its) potential negative impacts on the renegotiation with the EU".

Corbyn accused Johnson of "hijacking" the results of the original 2016 Brexit referendum.

He said Labour could back a vote of no-confidence in Johnson's government if lawmakers' last-ditch legislative manoeuvre fails.

"The vote of no confidence is very much there on the table," said Corbyn. "It's not an either or. Both options are absolutely there."