The agent for the two Jamaican stars implicated in an unfolding doping scandal laid blame for failed drug tests on the sprinters’ trainer, in a report published on early Tuesday.

Paul Doyle, the agent to Jamaican sprinters Asafa Powell and Sherone Simpson, told the New York Times that a Canadian trainer, Christopher Xuereb, had provided the track stars with a combination of supplements and injections that eventually led to the positive drug tests for his two clients.

“We were trying to figure out what went wrong, and it was pretty obvious to us where we needed to look,” Doyle was quoted in the report.

“There are many different things he was giving them, and we still don’t know which one caused the positive test. Most of the supplements he gave were for recovery or energy during workouts.”

Olympic gold medallists Powell and Simpson, along with three others, tested positive for the banned stimulant oxilofrine in out-of-competition tests. The announcement came on the same day that American sprinting star Tyson Gay acknowledged to also having tested positive for an unspecified substance.

The US star’s camp said it has launched an internal investigation and pledged to co-operate with authorities.

The Italian Police conducted an overnight raid of a hotel in Lignano Sabbiadoro, a coastal town in the north-east, where Powell and Simpson were staying with other Jamaican athletes. They seized suspect medicines and nutritional supplements, but did not arrest Powell’s coach.

The revelations come just five weeks before the athletics world championships in Moscow — where Gay was expected to face off against Usain Bolt in a battle of the world’s two fastest men. Gay has announced he is pulling out of the competition.

International Olympic Committee president Jacques Rogge, in a Monday statement, expressed his surprise and disappointment about the positive tests by Gay and Powell.

“I was surprised and disappointed, but I feel strengthened by the measures that have been taken by the US Anti-Doping Agency (USADA), the World Anti-Doping Agency (WADA), and the world of sport in general,” Rogge told the Around The Rings website.

“It’s always disappointing when you hear bad news but, at the same time, this is confirmation that out-of-competition testing really is effective.”

Gay also took a hit off the track as Adidas announced that it had suspended its sponsorship of the American star after the failed drug 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,” said Adidas — which has backed Gay since 2005 — in a statement.