Updated

The European Union's Brexit negotiator says the British government must keep up the momentum in negotiations on leaving the bloc if it wants the talks to move into a new phase in December.

Michel Barnier said Tuesday that "it's very important to maintain this constructive dynamic in the coming two months."

Barnier held dinner talks Monday with British Prime Minister Theresa May and European Commission President Jean-Claude Juncker as London seeks to broaden the Brexit negotiations.

The EU says it will only discuss future relations with Britain once "sufficient progress" has been made on the divorce bill, the rights of citizens hit by Brexit and the status of the Northern Ireland-Ireland border.

EU leaders are unlikely to broaden the talks at their summit this week but might do in December.