Justin Gatlin tested positive after unknowingly having testosterone cream rubbed into his legs by a massage therapist with a grievance, according to his coach Trevor Graham.

The Olympic and world champion failed the test at the Kansas Relays in April and faces a lifetime ban for a second offence following a positive test for an amphetamine at the 2001 US Junior Championships which was later overturned but not annulled.

The 24-year-old has protested his innocence and should learn his fate within a week in a hearing before the United States Anti-doping Agency (USADA).

However, Graham is insistent his athlete is the victim of sabotage and claimed on one occasion when he walked in on a massage session the therapist had quickly slipped a white jar of the substance into his pocket.

He told the Washington Post: "We know who the person is who actually did this.

"Justin is devastated. Myself, too. We are extremely upset right now. We are trying to go out and make sure we can prove his innocence, and we hope this individual has the guts to come forward and say he did it."

Graham believed the therapist may have thought Gatlin was involved in his firing but when confronted the therapist denied the charge.

Gatlin's lawyer Cameron Myler, however, moved yesterday to distance the legal team from Graham's claims of sabotage saying: "Trevor's comments were not made with the knowledge or authorisation of either Justin or us."

Graham himself is under investigation because of the large number of his athletes who have tested positive, the most famous being former world record holder Tim Montgomery, and was a key figure in the Balco scandal.

Gatlin's positive test was announced just days after Floyd Landis also tested for testosterone and the United States Olympic Committee have suggested it might be necessary to broaden the span of those who can be held accountable.

"We are thinking about broadening the scope of responsibility and accountability to include individuals who have the ability to influence the athlete, such as coaches, trainers and agents," said Darryl Seibel, a USOC spokesman.

He said the committee could deny those people access to the Olympic training centres, accreditation to the Olympics and access to high-performances services provided by the committee.