German T-Mobile rider Patrik Sinkewitz has tested positive for elevated levels of testosterone, the German cycling federation (BDR) said on Wednesday.
Germany's National Anti-Doping Agency (NADA) had informed the federation that a test on a first sample Sinkewitz gave on June 8 had shown increased levels of the hormone, the BDR said on its web site (www.rad-net.de).
The BDR said it would write to Sinkewitz, who has been suspended by T-Mobile, and he would then have five days to decide whether or not to request a second sample given on June 8 be tested.
If that confirmed the positive result, the BDR would take the case to the federal court for sport, the federation added.
In such an event T-Mobile would cancel the rider's contract, general manager Bob Stapleton said on Wednesday.
Speaking to reporters prior to the start of the 10th stage of the Tour -- a 229.5km ride from Tallard to Marseille -- Stapleton said: "He is suspended and if the analysis of the B sample is also positive his contract will be terminated."
Stapleton said the news was "extremely disappointing" but underlined his commitment to the fight against doping.
"This is an athlete who committed to our code of conduct. If he stepped outside it is extremely disappointing," he added.
"We support the test procedure and we support the sanctions even if it is an athlete of our team. It's good to see that it (the fight against doping) works.
"This increased testing is what our sport needs. It's in the best interests of the sport.
"When we decided to change the sport we knew that it would be risky. What we have to do is stay committed."
Meanwhile, UCI president Pat McQuaid told reporters: "My initial reaction is to wait for the B sample, then to comment. I think it is very unfortunate if this is the case."
Sinkewitz pulled out of the Tour de France earlier this week with a broken nose and a shoulder injury after a collision with a spectator.
The 26-year-old rider is still receiving treatment in a hospital in Hamburg, the BDR said.