Australian cyclist Michael Rogers has been provisionally suspended by the International Cycling Union after testing positive for clenbuterol.
The UCI announced the three-time former world time trial champion had tested positive at the Japan Cup Cycle Road Race in October.
The UCI said in a statement: "The decision to provisionally suspend this rider was made in response to a report from the WADA-accredited laboratory in Tokyo indicating an adverse analytical finding of clenbuterol in a urine sample collected from him in a test during the Japan Cup Cycle Road Race on 20 October 2013."
Rogers, who now races for Team Saxo-Tinkoff after spending two years at Team Sky, won bronze in the time trial at the 2004 Olympics in Athens.
The 33-year-old was world time trial champion in 2003, 2004 and 2005.
The UCI said the provisional suspension would remain in place until his national federation had investigated the case and determined whether he had committed an anti-doping rule violation.
Rogers has the right to request and attend the analysis of his B sample.