The United States Olympic Committee (USOC) confirmed on Monday that U.S. shot putt champion Kevin Toth has tested positive for the designer steroid tetrahydrogestrinone (THG).
USOC said in a statement it had been notified 30 days ago by the U.S. Anti-Doping Agency (USADA) that there was "sufficient evidence of doping" against Toth.
Toth tested positive for both THG and the stimulant modafinil at the U.S. championships at Stanford in California on June 21, 2003, it said. He also tested positive for THG a month later during an out-of-competition test on July 27.
Toth, 36, is disputing the results. He had previously been named in American newspaper reports but his identity had not been confirmed by officials until Monday.
Toth is one of four U.S. athletes, including world indoor 1,500 metres record holder Regina Jacobs, who have tested positive for THG, a previously undetectable drug modified to beat the testers.
The only non-American to test positive for THG is Britain's European 100 metres champion Dwain Chambers. He is due to face a UK Athletics independent disciplinary hearing on Thursday.