“And he will ask May how the UK plans to progress on the three key issues for phase 1.”

But Tusk, a former Polish prime minister, will say that progress on the divorce “will allow for a positive outcome” at the EU’s next Brussels summit on December 14 to move to the second phase, the sources said.

He will discuss with May the internal preparations the bloc is making for negotiations on future relations, including a possible trade deal and a transition period, the source added.

EU Brexit negotiator Michel Barnier warned last week that Britain had two weeks to meet the bloc’s conditions if it wanted a deal at the December meeting.

Failure to do so would push back a decision until February or March, leaving little time for trade talks before Britain leaves the bloc in March 2019.

The EU demands that Britain makes sufficient progress on a financial settlement, on avoiding a hard border between the British province of Northern Ireland and the EU state of Ireland, and on the rights of three million EU citizens living in Britain.