Francois Doumen risks the disqualification of two Auteuil jumping winners and possible punishment from the French racing authorities after his horses, Fulip and Indiana, tested positive to Calmagine, a medication used for colic.
The medication, which can only be administered by syringe, was found in samples taken from Fulip, a winner at Auteuil on June 27 and Indiana, who won at the same track on July 3.
Doumen has denied all knowledge and has reportedly filed a police complaint against the people or persons he claims to have deliberately administered the drug.
Interviewed by Equidia TV, Doumen, the trainer of well-backed King George VI Chase candidate, First Gold, said: 'We did not use this substance on our horses.'