BREXITEERS have warned the Prime Minister not to be too generous when she tries to settle Britain’s “divorce bill” with the EU.

As a committee of senior government ministers met in Downing Street to discuss how much it would cost to revive stalled trade talks, backbench Tory MP Nigel Evans told Theresa May not to “play Santa Claus”.

With news emerging that the Electoral Commission are looking into how much money Vote Leave spent on the Brexit referendum, and how it moved that money around, it will have been an awkward afternoon as some of the senior architects of that campaign met May to discuss the cost of their success.

The Exit and Trade (Strategy and Negotiations) Cabinet sub-committee, the so-called “Brexit war Cabinet”, contains Boris Johnson, Michael Gove, Liam Fox and David Davis.

Initial reports suggested Johnson, who previously said the the EU could “go whistle” over Brexit, was now cautiously backing an increased offer.

During her speech in Florence in September, May had committed the UK to paying €20 billion (£17.8bn).

She also promised Brexit would not end up costing any of the remaining 27 EU member states.

The new offer, which will factor in pensions and spending commitments the UK has already signed up to, will add a further €20bn to the bill.

Last week EU negotiators said the only way they would recommend the EU27 agree to start trade talks at next month’s summit was if more progress had been made on both the divorce bill and the Irish border.

During a radio interview pro-Brexit Tory backbencher Henry Smith told May not to put her hand in her

pocket: “Especially as Germany struggles to form a government, now is not the time for Britain to offer more money than her obligations are due in EU Brexit negotiations.

“The EU27 will of course miss UK cash but no deal would damage their economies and trade surplus with us far worse.”

The Downing Street divorce bill talks came as Amsterdam won a vote to host the European Medicines Agency.

The agency, along with the European Banking Authority, are to leave London, taking thousands of highly skilled jobs with them, after the UK leaves the European Union.

Meanwhile, the EU’s chief Brexit negotiator, Michel Barnier, has warned the UK not to embrace a bonfire of regulations if it wants a post-Brexit trade deal.

He said Brussels would offer the UK the “most ambitious” partnership on trade possible unless London expected member states to abandon their high standards.

With any trade deal needing to be ratified by individual member states and regional assemblies, Barnier seemed to hint that any deal would be vetoed if Britain was asking for too much.

Speaking in Brussels at a conference on the future of the EU, Barnier said: “The UK has chosen to leave the EU. Does it want to stay close to the European model or does it want to gradually move away from it?

“The UK’s reply to this question will be important and even decisive because it will shape the discussion on our future partnership and shape also the conditions for ratification of that partnership in many national parliaments and obviously in the European Parliament.”

He added: “I do not say this to create problems but to avoid problems.”

One other problem the Tories could face is a sizeable rebellion in the House of Commons tonight.

Tory rebel Dominic Grieve QC has tabled an amendment to the Government’s repeal Bill which would allow the EU’s Charter of Fundamental Rights to continue to apply domestically.

As well as a sizeable number of Tory rebels, Labour and SNP MPs are also set to back the amendment, which could lead to a defeat for May.

The SNP’s justice and home affairs spokesperson Joanna Cherry said: “Theresa May’s flailing government must drop its ideological opposition to the EU Fundamental Charter of Human Rights – which offers protection over a wide range of key rights not otherwise protected in domestic law – and ensure that it has its rightful place in our law.”