LONDON (Reuters) - The European Medicines Agency said on Friday it had started a formal safety review of Bayer's acne pill Diane 35 and its generic versions, following a request by France.

French authorities suspended sales of medicines last week after four deaths over the past 25 years were linked to their use. Bayer said at the time it was "surprised" by the suspension.

The European watchdog, which expects to give its view in May, said the risk of blood clots with the medicines was low but well known. It urged patients currently taking Diane 35 or one of its generics not to stop and to consult their doctors if they were concerned.

(Reporting by Ben Hirschler; Editing by Hans-Juergen Peters)