Floyd Landis walks away after a news conference in Madrid (file photo)

The secondary drug test of Tour de France winning cyclist Floyd Landis has come up positive for a performance-enhancing drug.

The Phonak cycling team fired the American shortly after the results were announced Saturday in Paris by the International Cycling Union.

The stunning cycling victory by Landis has been under a cloud of controversy since an initial urine test conducted after the 17th stage of the race showed an elevated testosterone ratio.

The case will now be referred to the United States Doping Agency, which could take several weeks to ultimately decide the matter.

The 30-year-old Landis could be stripped of his Tour de France title - the first time in its history a winner would be disqualified for doping. Second-place finisher Oscar Pereiro of Spain would be declared the winner.

The American could also receive a two-year ban from the sport.

Floyd Landis waves US flag as he rides down  Champs-Elysees  following final stage of Tour de France

Landis staged a remarkable comeback on the 17th stage of the Tour, overcoming a poor performance the day before to surge from 11th to third place overall.

His representatives have offered a number of explanations for the high testosterone to epitestosterone ratio in his first test, including thyroid medication for his ailing hip.

But The New York Times reported earlier this week that his initial urine sample turned up traces of synthetic testosterone.