The Court of Arbitration for Sport (CAS) ruled in favour of USA Track & Field (USATF) regarding 13 positive U.S. dope tests on Friday, ending a long-running saga with the sport's world governing body.

The U.S. governing body and the International Association of Atheltics Federations (IAAF) agreed to go to the CAF last April after the USATF refused to name 13 athletes who failed drugs tests, one of whom competed at the Sydney Olympics despite testing positive for an anabolic steroid.

A CAS statement on Friday said: "Based on its appreciation of the evidence as a whole, the unique facts and circumstances of this case constitute a valid and compelling reason why USATF should not be required to disclose the information in question to IAAF."

USATF had come under fire for refusing to release the names, with International Olympic Committee (IOC) chairman Jacques Rogge warning last year that the federation could face disciplinary action if it refused to co-operate.

The U.S. governing body argued that it could not breach its own confidentiality rules regarding athletes who produced positive "A" samples but who subsequently were not convicted of doping offences either because of laboratory error, medical rulings or other factors.

Reacting to Friday's ruling by CAF, a USATF statement read: "CAS ruled that although USATF was erroneous in its interpretation of IAAF reporting rules, USATF had regularly informed the IAAF of its confidentiality policies during the period in question, and the IAAF had not responded when asked if USATF policies were in conflict with IAAF rules.

"Therefore, CAS ruled, USATF reasonably assumed its policies were permitted under IAAF rules and that U.S. athletes had and continue to have a justified expectation of privacy and confidentiality."

The hearing disclosed several clashes between the IAAF and USATF. In 1998 the IAAF requested the names of athletes who had tested positive at the USA outdoor national championships but who had not been convicted.

In August 2000, shortly before the Olympic Games, the IAAF claimed that the USATF's failure to disclose information about a number of athletes was a breach of IAAF rules.

On both occasions the hearing found that USATF had written to the sport's governing body repeating that its confidentiality regulation prevented it from disclosing any details of the individuals involved.

In making its final judgement CAS endorsed USATF's insistence that throughout the 1996-2000 period the IAAF was fully aware of its confidentiality regulations and had never challenged or queried them.

CAS also ruled that as neither party should be considered to have "prevailed" each should bear the costs of its legal fees and other expenses in connection with the arbitration.

Both the IAAF and USATF agreed that the arbitration decision was final and binding.

"USATF looks forward to continuing to work together with the IAAF to pursue our mutual goal of growing and promoting the sport of track and field worldwide," the USATF statement added.