Olympic champion LaShawn Merritt suspended 21 months

US Olympic 400 metres champion LaShawn Merritt has been suspended through July 2011 after testing positive for a banned substance found in a male enhancement product, the US Anti-Doping Agency (USADA) said Monday.

The Beijing Olympic gold medallist had three samples test positive for prohibited testosterone prohormones, the anti-doping agency said in a statement.

He was suspended for 21 months, beginning October 28, 2009, the date of his first sample.                                           

Merritt had accepted in April a provisional suspension "as a result of positive drug tests caused by his use of an over-the-counter male enhancement product," the American athlete's attorney Howard Jacobs said in a statement at the time.                        

The statement said Merritt had used the over-the-counter product, which contained DHEA and pregnenolone, following the 2009 season.                                          

Neither Merritt nor Jacobs were immediately available for comment.