Athletics in drug crisis after sprint stars Tyson Gay and Asafa Powell test positive for banned substances Fellow Jamaican Sherone Simpson, a silver medallist in the women's 4x100m relay at the 2012 London Olympics, also tested positive at the trials for the same substance as Powell, while there were unconfirmed media reports in Jamaica that a further three unnamed Jamaicans had returned adverse findings. On Sunday night there were also reports from the Caribbean island that Powell's physical trainer, whose name has not been released, was detained by police in Italy and evidence was removed from his residence. The trainer had apparently only recently started work for the Kingston-based MVP track club, of which Powell and Simpson are both members. MVP is a rival training stable to Usain Bolt's Racers club and Bolt's agent, Ricky Simms, confirmed on Sunday that the triple Olympic champion had nothing to do with the latest drug cases. Gay, the American record-holder, had been in his best form in years this season with the three fastest 100m times in the world - an improvement he had attributed to being finally free of injury problems following surgery on a hip problem in 2011. The revelations on Sunday suggest a more sinister explanation. The American refused to reveal the substance for which he had tested positive but confirmed that his "A" urine sample had recorded an adverse finding and that he would now be asking for his B sample to be analysed. Technically, he is not guilty of a doping offence until the process is complete, but Gay is clearly resigned to his fate after admitting that he would not be competing in Friday's Diamond League meeting in Monaco or on the world stage in Moscow. Rarely does a B test contradict an A test. "I made a mistake," he said. I'm pulling out of Monaco and the World Championships. Gay added that he had informed team-mates, friends and family about the positive test, including his mother and daughter. They already know it is some type of accident. I don't want to use certain words, to make it seem like an accident, because I know exactly what went on, but I can't discuss it right now. Unfortunately, I have to break this news, that I have a positive A sample. Gay declined to go into details about the circumstances of the failed test but said he planned to give a full explanation to the United States Anti-Doping Agency. I have to go over everything with Usada first. I do realise and respect what I put in my body, and it is my responsibility. I'm going to be honest with Usada, about everything, everybody I've been with, every supplement I've ever taken, every company I've ever dealt with, everything. In a statement, the anti-doping agency said: "In response to Mr Gay's statements, Usada appreciates his approach to handling this situation and his choice to voluntarily remove himself from competition while the full facts surrounding his test are evaluated. The B sample will be processed shortly, and as in all cases, all athletes are innocent unless or until proven otherwise through the established legal process, and any attempt to sensationalise or speculate is a disservice to due process, fair play, and to those who love clean sport. Gay, whose American record of 9.69sec makes him the second fastest sprinter of all time, had previously taken part in a Usada campaign promoting drug-free sport. In a testimonial on the Usada website, Gay said: "I compete clean because I really believe in fairness, and besides that, my mom would kill me!