The UK says it will not pay a €100bn “divorce bill” to leave the EU.
Brexit secretary, David Davis insisted the UK would pay what was legally due, “not just what the EU wants”.
It comes amid claims by the financial times that the financial settlement sought by the EU has risen from €60bn.
Mr Davis said the UK treated its EU “rights and obligations” seriously but it had “not seen any number”, adding the EU was playing “rough and tough”.
The EU has insisted that the UK will have to accept liabilities stemming from its membership, including contributions to the EU budget
Many conservative MPs argue the UK does not owe the EU anything given the size of the contributions it has made over the past 40 years.
The EU’s chief negotiator Michel Barnier is due to publish his guidelines for the talks later although they are not likely to include any financial demands.