US 100 metres record holder Tyson Gay has said he had tested positive for a substance he could not identify and was pulling out of next month's world championships.
Gay, the 2007 world champion who had the year's fastest 100 metres time, said in telephone conference call he was notified by the US Anti-Doping Agency (USADA) on Friday that his A sample from an out of competition test in May had returned a positive.
"I don't have a sabotage story... I basically put my trust in someone and was let down"
"I don't have a sabotage story... I basically put my trust in someone and was let down," said Gay who insisted he had never knowingly taken a performance-enhancing drug.
"I made a mistake," said the 30-year-old sprinter from his training base in Amsterdam.
"I am pulling out of Monaco (this week's Diamond League meeting) and the world championships."
The B sample is yet to be tested, said a tearful Gay.
Shortly after the reports about Gay emerged, the Jamaican Gleaner newspaper reported several positive drug tests from the country.
Usain Bolt's agent Ricky Simms confirmed, though, that the Olympic champion was not among them.
He said: "I was just with him in Jamaica and we've had no information and we've not been contacted by anyone. It is not anyone that I'm connected with."