LONDON (Reuters) - Britain is legally bound to pay its up to 39 billion pound ($52 billion) divorce bill to the European Union before it agrees a future trade deal with the bloc, a Brexit minister said on Wednesday.

Anti-Brexit demonstrators wave EU and Union flags outside the Houses of Parliament in London, Britain, January 30, 2018. REUTERS/Toby Melville/File Photo

The remarks by Suella Braverman, a leading Brexit supporter, suggest Britain may not be able to use payment of the bill as leverage in talks on trade arrangements after it leaves the EU.

But a government source said ministers were trying to link the two in the negotiations, part of attempts to reassure Brexit campaigners who fear that Britain is coming off worse in the talks to end more than 40 years of union.

May has long said that “nothing is agreed until everything is agreed” in the Brexit talks, suggesting an accord on future ties must be settled before the divorce in March next year.

Stopping payments to the EU was one of the main reasons behind the campaign for Britain to leave the bloc, and Brexit campaigners have said they will not support the government’s plans unless they offer value for money.

While the government says it will present to parliament a detailed agreement on future ties well before the Brexit date, Braverman told lawmakers there was no legal link between the divorce bill and a deal on future trading arrangements with the bloc, only “a duty of good faith.”

“In the withdrawal agreement, there is agreed a duty of good faith ... which obliges both parties to cooperate in a way which means we are working constructively towards a future framework, which is mutually beneficial,” she told a parliamentary committee on Brexit.

“The duty of good faith should not be ignored in this context. It is more than just words and I think it does apply to the attitude in the way in which an agreement on the future framework will be struck.”

She also said if the terms of any future trade deal did not meet British demands, then London could renegotiate its terms.

Several lawmakers said parliament could be left voting on a financial deal worth 35-39 billion pounds in the withdrawal agreement due later this year without having legal certainty over what the future relationship would look like.

A spokesman for May said: “We have been absolutely clear that nothing is agreed until everything is agreed. We’re clear that we intend to agree the future framework at the same time as the withdrawal agreement.”

“Parliament will vote on the withdrawal agreement at the same time as the terms of our future relationship with the EU.”