American cyclist Tom Danielson says he tested positive for synthetic testosterone in an out-of-competition test performed in July.

Danielson, a former teammate of disgraced cyclist Lance Armstrong, said on Twitter that he did not take any banned substance.

The Cannondale Garmin team rider added that he was notified by the US Anti-Doping Agency that a sample collected on July 9 returned positive.

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As a result, Danielson withdrew from the Tour of Utah, where he was set to compete this week.

“I would never ever take anything like this especially after everything I have gone through the last years,” Danielson wrote on Twitter.

“This makes absolutely no sense.”

Danielson testified as part of USADA’s investigation into Armstrong and US Postal and had admitted to doping in the past.