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Italian police raided the hotel where Jamaican sprinter Asafa Powell is staying, and seized a number of supplements. Powell says they were given to him by his physiotherapist, and that he hopes to clear his name.
As he and other athletes await further test results, ITV News has had exclusive access to one of the labs fighting against drug cheats.
ITV News Sports Editor Steve Scott reports:
Italian police have raided the hotel where Jamaican sprinters Asafa Powell and Sherone Simpson are staying after they tested positive for banned stimulants, the Associated Press has reported.
Udine police captain Antonio Pisapia told the US news agency the rooms of the athletes and Canadian trainer Christopher Xuereb were searched and drugs were confiscated.
Pisapia reportedly said it is unclear whether the drugs are illegal and that the substances are being analysed.
Sportswear company Adidas has suspended its contract with Tyson Gay after the former double world sprint champion failed an out-of-competition dope test.
"We are shocked by these recent allegations, and even if we presume his innocence until proven otherwise, our contract with Tyson is currently suspended," a spokesman for the Germany-based company said.
Tara Playfair-Scott, Asafa Powell's publicist, issued a short statement on the sprinter's official Twitter account claiming that an individual "who gave Asafa the supplements" has been detained by Italian police.
Fellow sprinter Tyson Gay earlier suggested he had been "let down" by a nutritionist who had supplied him with sports supplements.
"I'm going to be honest with [anti-doping agency] USADA, about everything, everybody I've been with, every supplement I've ever taken, every company I've ever dealt with, everything," he said.
Neil Black, performance director at UK Athletics, says his sport is "stunned" by the news that the American sprinter Tyson Gay has failed a drugs test.
"The starting point was shock and amazement - how can this be?" he said.
"Then you rapidly go through to the tragedy, the shock to the sport, the disappointment, the fact that it doesn't do the sport any good whatsoever."
"It just triggers off to think if it is possible to be even more diligent in our awareness, if it is possible for us to remind athletes of their responsibility and accountability for all these things."
The agent for the former 100m world record holder Asafa Powell has confirmed that the athlete has tested positive for a 'stimulant' during a recent drugs test.
It is not clear if the athlete will now withdraw from future international competitions.
The former 100m world record holder Asafa Powell has tested positive for a banned substance, reports Reuters.
Powell competed against Tyson Gay at London 2012, and ran in the 100m final where he finished eighth.
Gay has revealed that he has also tested positive for a banned substance.
Latest ITV News reports
As Tour de France leader Froome can attest, the shadow of a drug scandal can linger for years. Athletics must act to avoid this cancer.
Paul Boyle, manager of Asafa Powell and Sherone Simpson, has confirmed that both have left Italy. They are in the air now.