Former 100-metres world-record holder Asafa Powell of Jamaica, American champion Tyson Gay and Jamaican Olympic gold medalist Sherone Simpson face suspension for testing positive for banned substances, puncturing the myth that the sport has cleaned up its act.
"I am not now nor have I ever been a cheat," Powell said in a message released through his Twitter account.
The 30-year-old Powell, who held the 100-metre record at 9.74 until Usain Bolt broke it in 2008, was calling for an investigation as to how a stimulant called oxilofrine entered his system and caused a positive test at Jamaica's national championships in June.
Simpson, who tested positive for the same stimulant, said she "would not intentionally take an illegal substance of any form into my system."
Gay, who has gone out of his way to promote himself as an anti-drug athlete, was more contrite but wasn't taking full responsibility.
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