On Sunday, Paul Doyle, representative for both athletes confirmed that they tested positive for the stimulant oxilofrine.
“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,” Powell said in a statement yesterday.
The news came the same day that American 100-meter record holder Tyson Gay admitted to taking a banned substance.
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Powell helped the Jamaicans to win the 400-meter relay gold medal at the 2008 Olympics and was the last man to hold the individual 100-meter record before countryman Usain Bolt broke it earlier that year.
Simpson won Olympic gold in the women’s 400 relay in 2004 and silver in 2012, along with an individual silver in the 100 in 2008.
These drug violations come one month after another Jamaican Olympic champion, Veronica Campbell-Brown, failed her drug test.