Prime Minister Theresa May chaired a meeting of her divided cabinet on Tuesday to discuss Britain's negotiations on leaving the European Union, as she fights to salvage a deal ahead of a crucial summit of EU leaders.

Eight eurosceptic cabinet members reportedly held informal talks late Monday, following rumours that some or all of them could resign over their opposition to May's plans.

"No one is resigning... We are trying to get the best deal for this country," one of the group, international development minister Penny Mordaunt, told the BBC early Tuesday ahead of the cabinet meeting.

A wider group of eurosceptics in May's Conservative party want the rebel ministers to persuade her to drop her "Chequers" plan for Brexit. If that fails, they could push the party to hold a confidence vote on May's leadership, The Telegraph reported.

May told parliament on Monday that a deal was still achievable, and that negotiations were in the "final stages" but held up by differences over how to keep an open border on the island of Ireland.

Her Conservative critics want her to drop her plan to accept a "backstop" for the border that would keep Britain in a "temporary," but potentially indefinite, customs union with the EU.

European Council President Donald Tusk warned EU leaders on Monday that a no-deal Brexit is "more likely than ever before," while calling for "every effort to reach the best agreement possible."