Floyd Landis' backup doping sample tested positive yesterday, increasing the prospect of the US cyclist being stripped of his Tour de France victory.
The International Cycling Union said Landis' "B" sample confirmed the initial "adverse analytical finding" for higher-than-allowable levels of testosterone.
Landis was immediately fired by his Swiss-based team, Phonak, and the Tour de France director said the 30-year-old rider was no longer considered the race champion.
In a further blow to Landis' defense, the head of France's anti-doping commission said the cyclist's samples contained synthetic testosterone, indicating his elevated levels were not produced naturally.
"I have received a text message from Chatenay-Malabry lab that indicates the `B' sample of Floyd Landis' urine confirms testosterone was taken in an exogenous way," French anti-doping council head Pierre Bordry said.
Landis has claimed the testosterone was "natural and produced by my own organism." If found guilty, Landis also faces a two-year ban from the sport. He continued to deny any wrongdoing and vowed to clear his name.
"I have never taken any banned substance, including testosterone," Landis said in a statement. "I was the strongest man at the Tour de France, and that is why I am the champion."
Landis' urine sample was analyzed at the Chatenay-Malabry lab outside Paris, and the second positive result was announced nearly two weeks after he stood atop the winner's podium on the Champs-Elysees in the champion's yellow jersey.
"The analysis of the sample B of Floyd Landis's urine has confirmed the result of an adverse analytical finding notified by the anti-doping laboratory of Paris on 26th July, following the analysis of the sample A," the International Cycling Union said.
The union said it was asking the US Cycling Federation to open disciplinary proceedings against Landis.