PARIS (AP) American cyclist Tom Danielson tested positive for synthetic testosterone in an out-of-competition test last month and was immediately suspended by his team on Monday.
Danielson, a former teammate of Lance Armstrong, said on Twitter that he did not take any banned substance.
''I would never ever take anything like this especially after everything I have gone through the last years. This makes absolutely no sense,'' said Danielson, who was once regarded as a potential Grand Tour contender.
The 36-year-old Danielson said the ''supplements'' he is taking might have triggered the positive result.
''I feel incredibly hurt, frustrated, and angry by this. I don't understand how or why this happened and still can't even accept this is true,'' he wrote. ''I will now, as I wait for the B test, have the supplements I take tested to see if this is what caused it.''
Danielson, who rides for the Cannondale Garmin team, added that he was notified by the U.S. Anti-Doping Agency that a sample collected on July 9 returned positive.
As a result, Danielson withdrew from the Tour of Utah, where he was set to compete from Aug. 3-9.
''Tom Danielson notified (us) that he was informed by USADA that he has returned an adverse analytical A sample using carbon isotope testing,'' his team said in a statement. ''In accordance with (our) zero tolerance anti-doping policy, he has been suspended from competition, effective immediately. He awaits the results (of) his B sample.''
Danielson testified as part of USADA's investigation into Armstrong and US Postal and has admitted to doping in the past. He was among five of Armstrong's teammates who accepted six-month doping suspensions in exchange for evidence that helped USADA to make the case to strip Armstrong of his seven Tour de France titles.