Irish jockey Oisin Murphy has vowed to "fight to clear my name" after testing positive for cocaine at a race meeting in France.
The 25-year-old British champion flat jockey denies taking the drug and is awaiting the result of a B sample following the test in July.
A statement issued by the Professional Jockeys Association (PJA) on Thursday said Murphy was selected for urine testing at Chantilly racecourse in France on July 19.
On August 19 he was informed by France Galop, the governing body of the sport in the country, that his "A" sample had returned positive for metabolites of cocaine.
The PJA said on the same day, Oisin organised for an independent laboratory to undertake hair sampling to prove his innocence, which returned a negative result.
"These results have been shared with France Galop and he awaits the results of France Galop's analysis of his "B" sample," the statement said.
Murphy said: "I have never taken cocaine in my life and will fight to clear my name.
"I want to thank those who are supporting me and in the meantime I want to keep riding winners and focus on my career."