British Prime Minister Theresa May leaves 10 Downing Street for parliament and another tense day of debate on her plans for Brexit

London (AFP) - Pro-Europeans in British Prime Minister Theresa May’s Conservative party warned Wednesday she must keep promises to give parliament a greater say over the final Brexit deal or risk a truce she needs to avoid a damaging defeat.

May narrowly avoided losing a major vote on the EU (Withdrawal) Bill in the House of Commons on Tuesday by offering last-minute concessions to Tory MPs who fear the government could decide on its own to leave the bloc with no deal.

But there is a dispute over what exactly she promised, with eurosceptics warning that there must be no question of allowing lawmakers the opportunity to undo Brexit.

May’s Downing Street office said she would publish a compromise amendment on Thursday, which will go to the upper House of Lords for debate on Monday, and then back to MPs.

Leading pro-European Tory MP Dominic Grieve said he hoped a compromise would be found, but warned that if not, “this isn’t the end of the matter”.

May, who leads a minority government propped up by the small Northern Irish Democratic Unionist Party (DUP), conceded on Wednesday that “we need parliamentary support” to implement Brexit.

But while ministers must be accountable to lawmakers, she told MPs that “the government’s hand in negotiations cannot be tied by parliament”.

She added: “I cannot countenance parliament being able to overturn the will of the British people.”

- A ‘real say’ on Brexit -

The Brexit talks are progressing painfully slowly, but both sides still hope to reach a deal in October ahead of Britain’s withdrawal from the EU in March 2019.

May has promised to give the British parliament a vote on the final deal, but the question is what happens if lawmakers decide to reject it.

On Tuesday, MPs overturned an amendment made by the Lords which would have given parliament the power to decide whether to leave the EU without a deal, keep negotiating – or stay in the bloc.

It followed a last-minute meeting with the prime minister and more than a dozen Tory MPs who considered supporting the motion.

One pro-European Tory, Nicky Morgan, told the BBC that May “understood that parliament wants to have a real say, in all circumstances, in relation to what’s going to happen in the Brexit deal”.

One compromise plan put forward by the rebels would ensure that if there was no Brexit deal by the end of November, ministers must seek parliament’s approval for its plan to proceed.

Eurosceptics urged the government to hold firm.

The rebels “seek a further parliamentary vote with the intent of overturning the decision of the British people,” Conservative MP John Redwood tweeted.

May has made an art of holding together the factions in her divided party, but it remains to be seen if she can find an amendment that prevents a rebellion from either side.

“We hope for support from all wings of the party when we bring forward Brexit policy,” a government source said.

- Scottish nationalist ejected -

MPs on Wednesday continued discussing Lords amendments on the EU (Withdrawal) Bill, with possible flashpoints on proposals to keep Britain closely aligned with the EU economy after Brexit.

In chaotic scenes before they started, Scottish National Party (SNP) MP Ian Blackford was ejected from the Commons after demanding an emergency debate on the impact of Brexit on devolution.

His party’s MPs walked out with him and he warned of a “constitutional crisis” with London.

The Scottish Parliament has refused to approve the Brexit bill, which it says would see London take back powers – albeit temporarily – from Brussels after Brexit that should by rights go to Edinburgh.