Olympic re-tests ordered

The IOC is trying to discover the extent of THG use

Olympic chiefs are to retest doping samples from the 2002 Salt Lake City Winter Games for the steroid THG.

International Olympic Committee medical director Patrick Schamasch said scientists would check as many as possible of the 642 samples taken.

Schamasch believes a large number of the samples being held in Los Angeles will be suitable for re-testing.

"We have been given the green light to go ahead and re-test these now," he said.

"The decision taken is in principle. Now we have to investigate in greater detail. I can not answer now exactly how many samples will be tested."

The IOC wants to leave no stone unturned in its fight against doping IOC spokeswoman

Lawyers have spent weeks probing the legality of re-testing and the IOC had been seeking scientific advice on whether the frozen 21-month-old samples remained viable.

The IOC had wanted to be sure the quality of the samples was still good so that there can be no question of legal issues regarding potential degradation.

"The IOC wants to leave no stone unturned in its fight against doping," said IOC spokeswoman Giselle Davies.

The discovery of THG (tetrahydrogestrinone) could see several big-name athletes miss next year's Athens Olympics.

Background: The THG scandal explained

Four US athletes have tested positive for THG, American officials have said, as has Britain's European 100m champion Dwain Chambers.

Chambers has protested his innocence, his legal advisors stressing that there has never been an admission by their client that he took THG or any other banned substance.

Athletics' ruling body the IAAF has re-tested samples taken at August's world championships in Paris to look for THG, discovering two positive tests.

Samples from this year's world swimming championships in Barcelona were also re-tested, but governing body Fina said there were no positive results.

Football's world governing body Fifa has ruled out retrospective tests for THG, saying samples are destroyed after 30 days in accordance with its doping control regulations.