Asafa Powell’s trainer has insisted he is not to blame for the Jamaican sprinter’s positive drugs test and claims he is being made a scapegoat.

Chris Xuereb, a Canadian, has had the finger of blame pointed at him by Powell's agent Paul Doyle after the sprinter and three-times Olympic medallist Sherone Simpson, both tested positive for the same banned stimulant oxilofrine.

Xuereb, who only began working with the sprinters in May, said in an emailed statement: “It is time the athletes took responsibility for their doping instead of looking around for a scapegoat whether that person is their therapist, bartender or anyone else.

“I am extremely disappointed that these athletes have chosen to blame me for their own violations.”

He added: "I did not provide any banned or illegal substances to Asafa Powell or Sherone Simpson. While I did recommend vitamins, all vitamins recommended by me were all purchased over the counter at reputable nutritional stores and were major brands.

“These athletes did not inform me that they were taking any additional supplementation other than what I recommended and it is obvious that these athletes were taking additional supplements that were not discussed or known to me.”

Xuereb pointed out that three other Jamaican athletes also tested positive at the same event where Powell and Simpson provided the samples, and that he had had no contact with the other three.

Prosecutors in Italy yesterday launched a criminal investigation into Powell, Simpson and Xuereb, who are at a training base in Ligano.

Authorities are investigating whether the trio have violated the law on doping. Italy is one of a few countries in the world that can impose criminal sanctions for doping offences on top of standard sporting sanctions.