Tour de France winner Floyd Landis has tested positive for the male sex hormone testosterone, the US rider's Phonak team said on Thursday.
"The Phonak Cycling Team was notified yesterday by (world cycling body) the UCI of an unusual level of testosterone/epitestosterone ratio in the test made on Floyd Landis after stage 17 of the Tour de France," Phonak said in a team statement.
Landis produced a remarkable effort a week ago to win the 17th stage of cycling's showpiece event following a disastrous 16th stage in which he dropped from first to 11th place.
Phonak said Landis would not ride until the matter had been clarified and said that if the B sample analysis confirmed the result of the A sample, the rider would be dismissed.
Phonak added: "The team management and the rider were both totally surprised by this physiological result.
"The rider will ask in the upcoming days for the counter analysis to prove either that this result has come from a natural process or that this is the result of a mistake."
Landis had earlier pulled out of a race in Denmark on Thursday. He also did not ride in a scheduled race in the Netherlands on Wednesday.
