Britain must agree way of calculating exit dues - EU's Barnier

BRUSSELS (Reuters) - The European Union's chief Brexit negotiator said on Wednesday that London and the bloc needed to agree on a clear way of calculating how much Britain owed before starting any talks about a future relationship.

"This is not a punishment, nor is it an exit tax of some kind. The Union and the United Kingdom have mutual commitments. They've committed to finance programmes and projects together," Michel Barnier told a news conference, adding this was a matter of settling the accounts

"Our objective in the first phase will be to agree with the United Kingdom on a rigorous methodology to calculate those obligations," he continued.

EU leaders have agreed a two-phase approach to Brexit talks, with commitments on citizens' rights, the budget and borders in phase one before talks about matters such as future trade relations between the bloc and Britain.

"Some have created the illusion that Brexit will have no material impact on our lives or that negotiations can be concluded quickly and painlessly. This is not the case," Barnier said.

(Reporting By Jan Strupczewski and Philip Blenkinsop)