Paris - American rider Tom Danielson has been suspended by his Cannondale-Garmin team after testing positive for synthetic testosterone but he denies taking a banned substance.
The team issued a statement on Monday saying Danielson had returned an "adverse analytical 'A' sample using carbon isotope testing" and had been suspended immediately.
Danielson, who is awaiting the results of his 'B' sample and could face a lifetime ban if that concurs with the 'A' sample, said on Twitter he had not used performance-enhancing drugs.
"While I was eating dinner with my team the night before the Tour of Utah I received a call from USADA notifying me that an out of competition test I gave July 9 has tested positive for, from what I understand, synthetic testosterone," Danielson said.
"I have not taken this or any other banned substance."
Danielson, 37, has already served a six-month ban, in 2012-13, after admitting to blood doping while riding with The Discovery Channel team.
The 37-year-old said he would skip the Tour of Utah, which starts on Monday. He won the race the last two years.
"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," added Danielson, who placed eighth in the 2011 Tour de France.