Former world 100 metres record holder Asafa Powell and Olympic 4x100 relay silver medallist Sherone Simpson have both tested positive for the stimulant oxilophrine at last month's Jamaican athletics championships.
In a statement on Sunday (July 14), Powell said he had tested positive for the stimulant, which has similar properties to ephedrine but a different chemical structure and is on the World Anti-Doping Agency's (WADA) banned list.
"I want to be clear in saying to my family, friends, and most of all my fans worldwide that I have never knowingly or wilfully taken any supplements or substances that break any rules. I am not now, nor have I ever been, a cheat," Powell said.
Powell, who has never won an individual global sprint title, held the 100 world record between 2005 and 2008 when his mark of 9.74 seconds was broken by current record holder and fellow-Jamaican Usain Bolt.
Simpson, who was a member of the Jamaican 4x100 metres relay team who won the silver medal at last year's London Olympics, said she had been notified that she had tested positive for the same drug at the trials.
The 28-year-old Jamaican finished equal second in the 100 metres at the 2008 Beijing Games and won a gold medal in the 4x100 relay in Athens four years earlier.
"This is a very difficult time for me," Simpson said in a statement.
"As an athlete, I know I am responsible for whatever that goes into my body. I would not intentionally take an illegal substance of any form into my system."
Jamaican Anti-Doping Commission (JADCO) chairman Herb Elliott confirmed the body had received "reports of adverse analytical findings from "A" samples".
"We cannot disclose any further information until the athletes have responded to notification of the "A" sample."
These positive tests follow American sprinter Tyson Gay's announcement that he had also tested positive for a banned substance that he could not yet identify.
Presented by Adam Justice