Michael Gove has said the PM must be given “flexibility” to negotiate a Brexit deal and he would not stop her if it meant paying more to the EU.
“I would not block the prime minister in doing what she believed was right,” he told BBC One’s Andrew Marr Show.
The so-called divorce bill has been one of the main sticking points in Brexit negotiations so far.
Theresa May has said the UK will honour commitments made but has not put a final figure on what will be paid.
But there have been reports that some Brexiteers are prepared for the UK to pay more than the 20bn euros (about £18bn) that has previously been suggested.
The money is among issues that must be resolved before the EU will agree to move on to talking about a transitional deal and future trade deal.
Last week, the EU’s chief Brexit negotiator Michel Barnier said the UK had two weeks to clarify what it would pay to settle its accounts, if the talks were to make “sufficient progress” before the next big EU leaders’ meeting in December.
On Sunday, he told French newspaper Le Journal du Dimanche he was making plans for the possible failure of talks, adding: “It’s not my (preferred) option… but it’s a possibility. Everyone needs to plan for it, member states and businesses alike. We too are preparing for it technically.”
Leave campaigner and entrepreneur James Dyson, also interviewed on the Marr programme, said it was “quite outrageous” for the EU to demand “billions and billions” before agreeing to negotiate on a future deal.
“I would walk away. I think that’s the only way to deal with them,” he said.
But Environment Secretary Mr Gove, who headed up the successful Vote Leave campaign during the EU referendum, said: “I can understand James’s point of view but on this occasion, respectfully, disagree with him.
“I think it’s far better for us to be engaged in these negotiations.”
Asked if he would block the prime minister if securing a deal meant the UK had to offer more money, he said: “I certainly would not. I would not block the prime minister in doing what she believed was right.”
“We have to make sure that when we are negotiating on money or anything else that we both respect Britain’s interests but also make sure, as the prime minister has said, that no EU country is out of pocket as a result of the decisions that we have made.”
“My view is the prime minister and [Brexit Secretary] David Davis should be given the flexibility that they need in order to secure that good deal.”
Asked about a Mail on Sunday story reporting that both Mr Gove and Mr Johnson had written to the prime minister expressing their “worry” that “in some parts of government the current preparations are not proceeding with anything like sufficient energy”.
He told the BBC: “As a departmental minister I have a responsibility .. to make sure that we are ready for any eventuality.”
He stressed the cabinet wanted to achieve a “good Brexit deal” but added: “We are also making sure that whatever may happen in these negotiations, that Britain can make the best of them.”