Theresa May and husband Philip attend the Lord Mayor's Banquet/ Reuters
Negotiations over the UK's departure from the EU are "now in the endgame", Theresa May says.
Addressing the Lord Mayor's Banquet in the City of London, the prime minister said the talks were "immensely difficult", but the sides were working "through the night" to make progress, according to BBC report.
"This will not be an agreement at any cost," the PM added. Mrs May will address her cabinet on Tuesday, with some ministers believed to want a change of plan.
BBC political editor Laura Kuenssberg said there was "huge frustration" in parts of the Conservative party and the cabinet about the PM's approach.
On Monday night, some cabinet ministers met for drinks in International Trade Secretary Liam Fox's office to discuss Brexit, including no-deal plans and the sticking point of the Irish "backstop".