10/15/2013 01:00 EDT | Updated 12/15/2013 05:12 EST

Taekwondo Olympian from Jamaica tests positive amid inquiry of nation's drug-testing agency

KINGSTON, Jamaica - A Jamaican who competed in taekwondo at the London Olympics says he has tested positive for a banned substance.

Kenneth Edwards said in a statement Tuesday he was notified about the results a month ago and he is awaiting results of a backup sample.

Edwards says he has not competed since July and there was no practical reason to use a diuretic for any kind of preparation. He says he will challenge the findings.

The announcement comes as the world's anti-doping authority launches a sweeping audit of Jamaica's drug-testing agency amid allegations of inconsistent testing.

Doping investigations also are underway involving other Jamaicans, including sprint stars Veronica Campbell-Brown, Asafa Powell and Sherone Simpson.