LOS ANGELES: US cyclist Tom Zirbel announced in a statement published on cyclingnews.com that he tested positive in an "A" sample doping test after the US Pro Time Trial Championships in August.

Zirbel said he was still awaiting the results of the "B" sample test, but had been notified by the US Anti-Doping Agency of the positive result for an endogenous steroid Dehydroepiandrosterone (DHEA).

"I want to inform the cycling community that an 'A' sample of mine from a urine test conducted by USADA on August 29, 2009 after the US Pro TT has tested positive for exogenous DHEA," Zirbel said in the statement. "I have not yet received notification from USADA on the findings of the 'B' sample, but I expect to receive word any day now."

Zirbel, 30, was contracted with the US-based Bissell Pro Cycling team from 2007-09. The noted time-trialer denied doping.

"The US Pro TT was a major objective of mine this season, but I would never compromise my integrity for any bike race," Zirbel said.

"At this point, I don't know how this happened but regardless of the outcome of my 'B' sample I intend to find out with the help of a few accomplished scientists and doctors who have selflessly helped me since I first was notified of the 'A' findings."