The International Association of Athletics Federations is still to confirm the positive test, but if Naman Keita did fail then he could face a two-year ban from sport.
Naman Keita said: "July was a catastrophic month for me in terms of performances and after the French championships I was suffering a little in my stomach.
"I was advised a dietary supplement to help the muscle regenerate and I ordered it off the Internet."
The French Athletics Federation are very disappointed that Naman Keita has failed the doping test and they were keen to point out that athletes should run any supplements past their doctors before using them.
