Former figure skater Sarah Abitbol, a bronze medallist with partner Stephane Bernadis at the 2000 world championships, recently published a book in which she said Beyer had raped her multiple times from 1990 to 1992.
Prosecutor Remy Heitz said in a statement that the preliminary investigation will look to "identify other victims who might have suffered... similar offences."
Beyer last week said that he had had "intimate" and "inappropriate" relations with Abibtol, who is now 44, in comments to Agence France Presse. Beyer could not immediately be reached for comment on Tuesday.
Sports minister Roxana Maracineanu on Monday asked French figure skating federation president Didier Gailhaguet, who at the time of the alleged rapes was already in charge, to resign. Gailhaguet has so far said only that he would "think about it". (Reporting by Jean-Stephane Brosse; Writing by Julien Pretot; Editing by Hugh Lawson)