BRUSSELS- A post-Brexit trade deal with the European Union is still possible, the EU's negotiator said on Wednesday, but called on London to give "clear signals" that it is ready to work towards one.

"Our problem is not related to timing, but to substance, in particular that the UK keeps backtracking on its commitments in the political declaration," Barnier told a think-tank event via video link, referring to the 31-page document that set out the direction of future negotiations, in October 2019.

"I believe that the deal is still possible," he said, adding that he was neither optimistic nor pessimistic but describing himself as determined.

(Reporting by Gabriela Baczynska and Jan Strupczewski; editing by Robin Emmott) ((robin.emmott@thomsonreuters.com; +32 2 287 6835; Reuters Messaging: robin.emmott.thomsonreuters.com@reuters.net))