LONDON – Tainted at the start, the Tour de France may have been tainted at the finish, too.

Floyd Landis’ stunning Tour de France victory was thrown into question Thursday when his team said he tested positive for high testosterone levels during stage 17. It was then that the 30-year-old American champion began his stunning comeback with a gritty charge into the Alps.

The Phonak team suspended Landis, pending results of the backup “B” sample of his drug test. If Landis is found guilty of doping, he could be stripped of the Tour title, and Spain’s Oscar Pereiro would become champion.

It wasn’t immediately known when the backup sample will be tested.

Efforts to reach Landis were not immediately successful. But Arlene Landis said her son called Thursday from Europe and told her he had not done anything wrong.

“He said, ‘There’s no way,'” she said in an interview at her home in Farmersville, Pa. “I really believe him. I don’t think he did anything wrong.”

Second-place finisher Pereiro said he was in no mood to celebrate.

“Should I win the Tour now it would feel like an academic victory,” Pereiro told The Associated Press at his home in Vigo, Spain. “The way to celebrate a win is in Paris, otherwise it’s just a bureaucratic win.”

The Swiss-based Phonak team said it was notified by the International Cycling Union (UCI) on Wednesday that Landis’ sample showed “an unusual level of testosterone/epitestosterone” when he was tested after stage 17 of the race last Thursday.

“The team management and the rider were both totally surprised of this physiological result,” the Phonak statement said.

Landis made a remarkable comeback in that Alpine stage, racing far ahead of the field for a solo win that moved him from 11th to third in the overall standings. He regained the leader’s yellow jersey two days later.

Phonak’s statement came a day after the UCI, cycling’s world governing body, said an unidentified rider had failed a drug test during the Tour.

Phonak said Landis would ask for an analysis of his backup sample “to prove either that this result is coming from a natural process or that this is resulting from a mistake.”

Phonak manager John Lelangue said the team would ask for the second sample to be analyzed in the next few days.

“He will be fighting … waiting for the B analysis and then proving to everyone that this can be natural,” Lelangue said in a telephone interview.

Arlene Landis said it could take two weeks for the results of the backup test to be made public.

“Of course he wasn’t happy about it, but they’re spoiling everything he’s supposed to be doing right now,” she said. “Why couldn’t they take care of this before they pronounced him the winner? Lance (Armstrong) went through this too. Somebody doesn’t want him to win.”

“Why do they put you through two weeks of misery and spoil your crown? My opinion is when he comes on top of this everyone will think so much more of him. So that’s what valleys are for, right?”

UCI spokesman Enrico Carpani said Landis was notified of the test Wednesday morning. He said the cycling body doesn’t require analysis of the “B” sample, but that Landis requested it.

“We are confident in the first (test),” Carpani said. “For us, the first one is already good.”

“It is obviously distressing,” Tour director Christian Prudhomme said at a Paris news conference, stressing the backup test still must be done. Prudhomme said it would be up to the UCI to determine penalties if Landis is found guilty of doping.

Also Thursday, one of Germany’s main television channels threatened to drop coverage of the Tour de France because of Landis’ doping test. The ZDF channel demanded guarantees from the UCI and tour organizers that they will take firms steps against doping.