STOCKHOLM - A comprehensive agreement on the future relationship between the European Union and Britain will take more time to agree than the 11-month transition period that begins when the UK leaves the EU at the end of January, the EU's chief negotiator said on Thursday.

"We simply cannot expect to agree on every single aspect of this new partnership in under one year," Michel Barnier said in a speech in Stockholm.

"We are ready to do our best and to do the maximum in the 11 months to secure a basic agreement with the UK, but we will need more time to agree on each and every point of this political declaration."

(Reporting by Jan Strupczewski in Brussels and Simon Johnson in Stockholm; Editing by Toby Chopra) ((simon.c.johnson@thomsonreuters.com; +46 8 700 1045; Reuters Messaging: simon.c.johnson.reuters.com@reuters.net))