The UK has only 10 days left to deliver on all three areas of its divorce terms with the European Union if London wants to start talks on a transition period after Brexit and a future relationship, the chairman of EU leaders Donald Tusk said.

"We need to see progress from UK within 10 days on all issues, including on Ireland," Tusk tweeted on Friday after a meeting with British Prime Minister Theresa May in Brussels.

"Sufficient progress in Brexit talks at December council is possible but still a huge challenge," he said on Twitter.

An EU official said that May agreed in the one-hour discussions that Dec. 4 was the "absolute deadline" to allow the EU's Brexit negotiator Michel Barnier to recommend moving onto the next stage on trade and future ties.