Solicitor Christopher Stewart-Moore released a statement confirming the Medical Committee of the French authority are planning a hearing.
The statement said: “On behalf of Frankie Dettori I can confirm that, as a consequence of a positive test at Longchamp on September 16 2012, he will be the subject of an inquiry by the Medical Committee of France Galop next week.
“In compliance with, and out of respect for, the regulations of France Galop, he will not be commenting further until the France Galop procedures have been completed.”
Dettori, 41, had four rides at Longchamp on September 16, a day of major trials for the Prix de l’Arc de Triomphe meeting last month.
The Italian partnered Marco Botti’s Joshua Tree to finish third in the Qatar Prix Foy, while the John Hammond-trained Sarah Lynx trailed home last in the Prix Vermeille.
He was then beaten just a head into second on Godolphin’s Farhh in the Prix du Moulin and was third for his former employers on Willing Foe in the Prix Gladiateur.
France Galop have not commented and in previous similar cases they have not issued a statement before the hearing.
Last month, Dettori’s 18-year association with Godolphin came to an end, with the jockey planning to ride as a freelance next year.