Jockey Frankie Dettori was temporarily suspended from racing in France on Wednesday following a positive drug test.
Dettori, one of the world's best known riders, tested positive for an unidentified banned substance on September 16 after riding at Longchamp.
The French association's medical committee, which held a hearing into the case Tuesday, said it was temporarily suspending the British-based jockey 'based on medical grounds.'
The panel transferred the case to governing body France Galop, which must decide whether to open its own investigation and extend the suspension.
"Stewards will be studying the file within the next fortnight before deciding what action will be taken in accordance with the Rules of Racing," France Galop said.
The 41-year-old Dettori, a three-time champion rider in Britain, is best known for riding seven winners on one day at Ascot in 1996.
The suspension lasts at least until Dettori's next hearing before France Galop, which could take place in two weeks, spokesman Julien Pescatore said. No date has officially been set.
There are two race meetings at Deauville on December 4-5 but they are not Group 1 and Group 2 races, so Dettori effectively misses very little in the next two weeks. Dettori competed at the prestigious Arc de Triomphe race last month, finishing seventh on Camelot.
On Tuesday, the French medical committee met for about two hours with Dettori's lawyer Christopher Stewart-Moore.
The identity of the banned substance in Dettori's case is covered by medical confidentiality under French law.
Irish jockey Kieren Fallon was banned for six months by France Galop in 2006 after testing positive for a banned substance. France Galop then banned him a further 18 months after a second positive test in August 2007.
Dettori was cautioned by police in Britain for possession of cocaine in 1993.