German Olympic Committee have confirmed that an unnamed athlete has failed a drug test at Sochi.
The German Olympic Sports Confederation (DOSB) said that it had been informed by the International Olympic Committee that the "'A' sample of a member of the German Olympic team produced a result that diverged from the norm".
The 'B' sample will be tested later on Friday while a session of the IOC's disciplinary commission will also take place over the issue, the DOSB said in a statement on its website.
The IOC would not confirm or deny the positive test, staying in line with its procedures on any doping investigations.
"I won't comment on whether a process is even underway," IOC spokesman Mark Adams said.
Stefan Schwarzbach, the German team spokesman for cross-country and biathlon, said he wasn't allowed to comment on whether the test involved those events or another sport.
"All I can say is, we have a positive 'A' sample (somewhere on the German Olympic team)," he said. "But as long as we don't have a positive 'B' sample, we are not allowed to talk about that."