Melbourne:Former world champion and Olympic medallist Ato Boldon has tested positive to the banned substance ephedrine. This was announced by the International Association of Athletics Federation (IAAF). IAAF General Secretary Istvan Gyulai told a press conference in Melbourne that Boldon had tested positive at a meet in the United States in May but would not be suspended because the offence only carries a warning. The 27-year-old won the 200m title at the 1997 World Championships. He also won a silver in the 100m and bronze in the 200m at last year's Sydney Olympics.