The EU's chief negotiator Michel Barnier is holding talks with his UK counterpart Lord Frost with time running out for a deal on a post-Brexit trade agreement.
Boris Johnson has said he wants an agreement in place by the time of next week's EU summit in Brussels starting on Thursday.
While both sides have reported progress in the negotiations, there remain significant issues, particularly on the issues of fisheries and state aid.
The meeting in London comes after Mr Johnson and European Commission president Ursula von der Leyen agreed at the weekend to intensify negotiations in a final push for an agreement.
Speaking in Dublin on Thursday, the European Council president Charles Michel said they had reached a critical stage.
"The coming days are crucial, this is the moment of truth," he said.
"I have been very clear with Prime Minister Johnson.
"It's now for the UK to restore trust and to put all its cards on the table.
"The EU is doing its utmost to find an agreement with the UK, but not at any cost."
Negotiations are due to resume again in Brussels next week as the discussions go down to the wire.
The Prime Minister's official spokesman said on Thursday: "We have been perfectly clear about the need to work towards the October 15 European Council, the EU has agreed to intensified talks, those have been taking place this week and you will see more of them next week."