(Agencies)
Updated: 2007-11-16 11:13

MADRID - World Anti-Doping Agency chief Dick Pound said on Thursday he wanted an audit of all doping tests that U.S. sprinter Marion Jones had passed before she admitted in October to taking peformance-enhancing drugs.

Marion Jones cries as she makes a statement to the media after leaving the U.S. Federal Courthouse in White Plains, New York, October 5, 2007. [Agencies]

Jones who won five medals, including three golds, at the Sydney 2000 Olympics, had tested negative for drugs in 160 tests.

"It is not much fun to find that someone who has been tested 160 times admits to doping," Pound, attending the World Conference on Doping in Sport, said.

"We would like an audit of these tests. What was she tested for, how many in and out-of competition," Pound said.

"I am not happy to hear that someone who had so many tests was a user for so many years."

Pound said testing was becoming more sophisticated.

"The science is catching up with what's going on," he said. "You can test for more things and our list is a little more flexible."

A British scientist though told the BBC tests for human growth hormone (HGH) could detect only "a stupid athlete".

Peter Sonksen, an emeritus professor of endocrinology at St Thomas' Hospital in London and a visiting professor at Southampton University, has studied HGH for over 40 years and during that time has advised the International Olympic Committee (IOC) and the British authorities on the issue of doping.

"The test we have is imperfect and it's probable that an awful lot of people who appear to be negative are in fact doping," he told BBC Sport.

"Until we have a more effective test, you can't believe what you're seeing."

HGH appeals to athletes as they can gain considerable strength, burn off fat and reduce recovery time from rigorous training thus improving their stamina.