The test on Sinkewitz was carried out June 8, a month before the start of the Tour, and the A sample came back positive, the German cycling federation said today.

Sinkewitz has been provisionally suspended by his team, T-Mobile spokesman Stefan Wagner said.

TV stations ZDF and ARD, two public channels which have been broadcasting the Tour, said they were dropping their coverage "until further notice."

Sinkewitz has five days to decide whether to request a B sample test. If that also comes back positive, he faces a possible ban. He also would be fired by his team and have to pay back his annual salary.

"It's not possible. I know nothing about it," Sinkewitz told the German news agency DPA from a Hamburg clinic. "I am about to have surgery. I can't deal with it now."

Sinkewitz competed in the Tour, which began in London on July 7, but dropped out after crashing into a spectator after stage 8 on Sunday.

The rider is being treated for facial injuries, including a broken nose, and other injuries.

While elevated testosterone levels do not necessarily indicate doping, Sinkewitz was reportedly six times over the limit.

His case is the latest to shake German cycling in the past few months.

Several former riders for Telekom, now renamed T-Mobile, admitted using performance-enhancing drugs in the 1990s, including Bjarne Riis, a Dane who won the Tour de France in 1996.

Jan Ullrich, who won the 1997 Tour, has denied any wrongdoing but retired in February after being implicated in the Spanish blood-doping scandal known as Operation Puerto.

Just before the start of this year's Tour, Joerg Jaksche became the first rider to admit using blood doping prepared by a Spanish doctor. Jaksche was suspended by his team — Tinkoff Credit Systems — in May.

T-Mobile's current anti-doping program is considered among the most rigorous in cycling.

The sports' anti-doping director, Anne Gripper of the UCI, told The Associated Press in June that the "very robust" anti-drug programs implemented by T-Mobile and the Danish CSC team mean "it would be almost impossible for the riders in those teams to even consider any form of doping."

T-Mobile spokesman Christian Frommert said the latest case, if confirmed, was a "clear setback" in the team's anti-doping policy.