Berlin (AFP) - German Chancellor Angela Merkel on Wednesday snubbed British PM Theresa May's call for negotiations on the UK's exit from the European Union to run alongside talks on defining their future relationship.

"The negotiations must first clarify how we will disentangle our interlinked relationship... and only when this question is dealt with, can we, hopefully soon after, begin talking about our future relationship," Merkel said in Berlin.

The German leader also called for "fair and constructive" negotiations with Britain, saying that "we, the EU, would carry out the upcoming talks in a fair and constructive manner".

"I hope that the British government will also adopt the same spirit in the negotiations," Merkel said, adding that May had given her such an assurance in a phone call on Tuesday.

Merkel said that securing the future of EU citizens living in Britain would be among the priorities in the negotiations.

"The government will try to minimise as much as possible the impact on the daily lives of those affected," she said.

Merkel also expressed her wish for Britain and the EU to remain close partners.

At the same time, although the EU will be engaged in intensive Brexit talks over the next two years, it will also "continue working in parallel on several important tasks" that concerns the bloc, she said.

"The EU is a unique historic success story, it remains so after Britain's exit," she said.