Sprinter Ato Boldon of Trinidad tested positive to the banned substance ephedrine at a meeting in the United States in May, the IAAF said today.
Istvan Gyulai, general secretary of athletics' world governing body, confirmed Boldon's positive test at a media conference in Melbourne.
Boldon, 27, will not be suspended as the offence only carries the penalty of a public warning.
Boldon has three Olympic bronze medals and one silver. He finished a lowly fifth in the Goodwill Games 100m race in Brisbane Wednesday and pulled out of the 200m, citing "recurrence of a pre-existing injury".
He trains with world record holder Maurice Greene under coach John Smith and finished fourth in the 100m at the recent world championships in Edmonton.
Greene pulled out of the Goodwill Games with a hamstring injury.
Earlier this week French sprinter Christophe Cheval was banned for two years by the French Athletics Federation after testing positive for nandrolone at the world championships last month.
More than 350 athletes are being tested for banned performance enhancers at the Goodwill Games, including steroids, testosterone and masking agents.
AFP