Conservative MP Jacob Rees-Mogg | Oli Scarff/AFP via Getty Images Brexiteers demand itemized EU bill Euroskeptics worry the UK government has given too much.

LONDON — The U.K. appears to be "dancing to the tune of the European Commission" in the Brexit negotiations, prominent Brexiteer Jacob Rees-Mogg told MPs during a House of Commons debate on the government's decision to increase its financial offer to the EU.

Euroskeptic MPs denounced the government's decision and demanded to see an itemized bill, plus a guarantee that the U.K. would not pay up unless the EU granted it a trade deal.

A senior government minister confirmed to POLITICO that the U.K. had agreed to dramatically expand the scope of the financial commitments it is willing to cover. Although the final bill remains "guesswork" according to the minister, it has been estimated at between €45 billion and €55 billion.

Responding to an urgent question in the House of Commons following reports of the financial offer Tuesday night, Chief Secretary to the Treasury Elizabeth Truss said press reports were "speculation" and negotiations are "ongoing."

"Nothing is agreed until everything is agreed," she said.

But Euroskeptics on both the government and opposition benches expressed anger at the government's apparent concession on the bill. Speaking during the debate, Rees-Mogg urged the government to "note the growing concern" that it seemed to be "dancing to the tune of the European Commission" in negotiations. He called for certainty that no payments to the European Union would be made in the absence of a "full agreement covering trade" after March 29, 2019.

Another prominent Brexiteer, Peter Bone, warned the U.K. government that his constituents would not want "£60-odd-billion" to be handed to the EU claiming "such a move would be betraying the trust of the British people.”

He was supported by Labour MP Dennis Skinner, who also backed Brexit. He told MPs that if the government had £60 billion "to spare" it should spend it on the NHS and social care.

Another Tory backbench MP, Philip Davies, called for an "itemized account of exactly what [the U.K. is] paying for" and "the legal basis upon which we are making those payments," before a vote on the final bill. Former Tory Minister Jonathan Djanogly agreed that payments should be itemized.

Former Northern Ireland Secretary Owen Paterson said there should be "no legally binding commitment to spend money" until the EU agrees to "a serious free trade agreement based on reciprocal free trade and zero tariffs."

Former Brexit Minister David Jones said May had made a very “fair and generous” offer in her Florence speech and it was “high time" the European Union started adhering to the obligations in Article 50 that negotiations take account of the future relationship.

Truss insisted that the potential payments would be "value for money" and it was in U.K. interests to secure a long-term economic partnership.