British Prime Minister Theresa May meets representatives during a visit to the Airbus area at the Farnborough Airshow in Farnborough, England. Picture: Matt Dunham/AP

London - British Prime Minister Theresa May will face the anger of Brexit supporters in her party on Monday when they try to force her to change course on her strategy for leaving the European Union.

May is battling for her political survival after announcing a negotiating plan that infuriated factions on both sides of her Conservative Party: eurosceptics say the plan leaves Britain too close to the EU, while pro-European lawmakers say it leaves the country too distant.

The threat to her position from the Brexiteers should become clear on Monday when they put forward a series of proposals to toughen up the government's customs legislation during a parliamentary debate.

May is not expected to be defeated on the amendments, and could even order her government to back some of the least controversial ones to neutralise the impact of the rebellion without watering down her exit plan.

But, if she chooses to fight and then sees a large number of her own party rebel, it would undermine her leadership and cast fresh doubt on whether she can deliver the Brexit plan agreed by her cabinet this month at her Chequers country residence.

The Chequers agreement, which is only a starting point for negotiations with the EU, has already led to the resignations of her Brexit minister David Davis and foreign secretary Boris Johnson, and the eurosceptic faction say it has to change.

Conservative lawmaker John Baron said he had remained loyal to May, believing her to be honourable in trying to respect the result of the 2016 referendum when Britons voted to leave the EU.

"I have played my part to seek consensus for a clean Brexit. However, having examined the Chequers agreement ... I have come to the conclusion that it does not respect the referendum result – it is not what people voted for," he said.

Some in the pro-EU faction have also rejected the plan. Former minister Justine Greening called on Monday for a second referendum to end the stalemate in parliament over the best future relationship with the bloc.

May's spokesman said there would be no second referendum under any circumstances, and restated her position that the Chequers plan was the only way to deliver a Brexit that worked in the best interest of the country.

Another pro-EU lawmaker Dominic Grieve, who has led previous efforts to get the government to soften its Brexit stance, said the party needed to accept compromises "or accept that Brexit cannot be implemented and think again about what we are doing".

'MY BREXIT OR NO BREXIT'

On Sunday, May attempted to face down would-be eurosceptic rebels by warning that if they sink her premiership then they risk squandering the victory of an EU exit that they have dreamed about for decades.

A party meeting last week looked to have snuffed out talk of a confidence motion challenging May's leadership, which would require 48 Conservative members of parliament to initiate, and 159 to win.

But, fuelled by criticism from U.S. President Donald Trump and anger among grassroots party members, the sentiment against May has gained fresh momentum.

A ministerial aide became the ninth party member to resign their post in protest over the Chequers deal. Lawmaker Scott Mann quit on Monday, saying the plan would put him in conflict with his constituents by delivering a "watered down" Brexit.

The debate is expected to start at 1630 GMT, later than originally planned, with the first votes due around 2000 GMT.

The amendments to the Taxation (Cross-border Trade) Bill have been proposed by arch-eurosceptic Jacob Rees-Mogg. He said he did not expect the bill, or another bill on trade due to be debated on Tuesday, to be blocked outright by the 650-member parliament.

"I'm sure Theresa May does not want to split the Conservative Party and therefore she will find that the inevitable consequence of the parliamentary arithmetic is that she will need to change it (the Brexit policy) to keep the party united," Rees-Mogg said. "We'll have an idea of the numbers, I suppose, at 10 o'clock on Monday evening."