Swimmer Jessica Hardy's trip to the Beijing Olympics could be in jeopardy after testing positive for a banned substance, according to a person familiar with the test results.

Hardy's "A" sample from the recent U.S. Olympic trials tested positive, the person told The Associated Press on Wednesday night. The person requested anonymity because he was not authorized to speak publicly.

The Swimming World magazine Web site first reported the positive doping test.

Mark Schubert, head coach and general manager of the U.S. team, along with Hardy's agent and personal coach at Southern California did not immediately return phone messages left by the AP.

The Web site nbcolympics.com reported Hardy's backup "B" sample also tested positive.

If so, the 21-year-old swimmer from Long Beach can pursue appeals with the American Arbitration Association and the Court of Arbitration for Sport. Any ruling by CAS would be final and binding.

Hardy's name was among the 596 athletes officially entered into the Beijing Games on Wednesday by the U.S. Olympic Committee.

Hardy earned spots on her first Olympic team in her best event, the 100-meter breaststroke, and the 50 freestyle and 400 free relay.

"I don't think if you had told me a month ago that I would make it in all three of these events that I would have believed you," she said at the trials. "I'm expecting good things for sure."

Hardy burst onto the international scene at the 2005 world championships in Montreal, where she broke the world record in the 100 breast. Her time still stands as the American record.

She swam at California for two seasons, winning the 100 breast at the 2006 and 2007 NCAA championships before turning pro. She trains at USC with coach Dave Salo.

In Beijing, Hardy was expected to be a medal threat in the 100 breast, and to play an important part on the 400 free relay, and possibly the 400 medley relay.