Asafa Powell, Sherone Simpson and Tyson Gay
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Athletes Gay, Powell and Simpson fail drug tests

US sprinter Tyson Gay and Jamaica's Asafa Powell and Sherone Simpson have failed drug tests.

Gay, 30, the joint-second fastest man over 100m, was notified by the US Anti-Doping Agency on Friday that his A sample from an out-of-competition test in May had returned a positive.

Powell tested positive for a banned stimulant while competing in June's Jamaican championships. Simpson also failed a drug test at the event.

All three have issued statements to say they took the substances unintentionally.

Nick Davis reports from Kingston, Jamaica.