The EU's chief Brexit negotiator Michel Barnier on Wednesday dismissed as "rumours" reports of a deal between London and Brussels on Britain's exit bill.

Both the Daily Telegraph and the Financial Times reported, citing diplomatic sources, that London and Brussels had agreed on Britain's financial obligations but had not settled on an exact amount for the so-called divorce bill.

Both sides have now accepted the British will pay between 45 and 55 billion euros ($53-63 billion), with the final figure depending "on how each side calculates the output from an agreed methodology", the Telegraph said.

Meanwhile the FT reported Britain would cover EU liabilities worth as much as 100 billion euros, but if structured as net payments over many decades, that could drop to less than half that amount.

But speaking in Berlin at a security conference, Barnier described the reports as "rumours".

"There is a subject on which we are continuing to work -- despite the claims or rumours in the press today, that's the issue of financial engagements," Barnier said.

"We are not going to have 27 (EU members) pay for what was decided by 28, it's as simple as that. So we want to settle the accounts," said Barnier.

Asked about the reports, a spokesman for Britain's Department for Exiting the European Union said "intensive talks" are taking place in Brussels this week, and did not address the divorce bill directly.

The European Commission declined to comment.

An agreement would be a major breakthrough as Britain prepares for an EU summit in December where it is hoping to get the go-ahead to start the next phase of talks on future trade ties with the EU.

It would leave two major areas on which the two sides still do not agree -- expatriate citizens' rights after Brexit and the future of the Irish border.