May under pressure to justify paying higher Brexit divorce Bill

The prime minister will attempt to reach a consensus over a proposed offer at a meeting of her cabinet committee on EU strategy on Monday as the UK tries to break the deadlock in Brexit negotiations.

But some of the leave-supporting ministers, including Boris Johnson and Michael Gove, are understood to be applying pressure behind the scenes to make sure that the UK has a clear idea what it wants from a future trading relationship before agreeing to hand over such a large sum.

They are likely to press the prime minister to begin cabinet discussions on the UK's future trading relationship after the pair sent a joint letter to No 10 in recent weeks demanding an arrangement that allows Britain a wide degree of regulatory freedom. Philip Hammond confirmed on Sunday that the UK would make an improved offer to the EU within three and a half weeks, after Michel Barnier, the EU's chief negotiator in Brussels, said Britain had a fortnight to break the impasse.

"We will make our proposals to the European Union in time for the council [on 14 December], I am sure about that," the chancellor told the BBC's Andrew Marr Show. He promised Britain would honour its debts but also "negotiate hard" on the various aspects of the financial settlement.

However, senior Brexiters are particularly concerned about the idea of signing over a high sum as part of the withdrawal agreement but later ending up with an unsatisfactory deal on the future relationship. Johnson is not thought to be opposed in principle to a divorce bill higher than the £20bn already offered by May but would need assurances that the UK was heading for the right type of relationship with the EU when it leaves. At the moment, there is a cabinet agreement on seeking a two-year transitional period after Britain leaves the EU in March 2019, but nothing has been agreed on what the future relationship should look like after that.