RALEIGH, North Carolina - Olympic and world 400m champion LaShawn Merritt has failed three doping tests for a banned substance and accepted a provisional suspension, his lawyer said on Thursday.

"LaShawn Merritt has accepted 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.

"His voluntary acceptance of a provisional suspension means that he has chosen not to compete until the case has been decided," the statement added.