EU President Donald Tusk warned Britain on Friday that it had until early December to make "much more progress" on divorce terms in order to unlock Brexit trade talks by the end of the year.

Reflecting growing impatience with London, Tusk's deadline followed talks with British Prime Minister Theresa May on the sidelines of an EU summit in Sweden that was meant to focus on reforms for the bloc's post-Brexit survival.

The European Union has for months demanded that Britain make "sufficient progress" on its divorce bill, citizens' rights and the Irish border in order to move on to talks about a future trade deal and transition period.

"We need to see much more progress on Ireland and on the financial settlement," Tusk, a former Polish prime minister, said at a press conference after the summit in the port city of Gothenburg.