Britain has been given an ultimatum by the EU's chief Brexit negotiator Michel Barnier.
Following another round of talks with David Davis and his team, Barnier said that the UK now has two weeks to make concessions if it wants to make any progress by December.
The UK needs to clarify what it will pay in the so-called "divorce bill", he said, or risk not progressing onto discussions about trade by the end of the year.
Finding a solution for the Irish border also remains a key issue. A leaked document from the EU appeared to propose keeping Northern Ireland in the customs union to avoid a hard border on the island of Ireland. But Davis said he would not accept a border between the island and Great Britain.
However, Barnier said that some progress had been made on citizens' rights, after the UK provided "useful clarifications" on how a new system would work.
“Now is the time for both sides to move together to seek solutions," said David Davis.
“This is a serious business. If we are to find a way forward it will require flexibility and pragmatism from both sides."