A BBC investigation reports serious questions hanging over a key drug test for EPO, Matt McGrath BBC science correspondent reports, just two weeks before the start of the Beijing Olympics. The BBC believes that labs are classing positive tests for the blood-boosting drug EPO as negatives.
Some samples have been described as suspicious - giving rise to fears that no action will be taken against cheats, as several endurance events athletes have had their first sample test positive but were cleared on the second or B test.
The World Anti-Doping Agency (WADA) tightened the criteria by which an EPO positive could be declared. However leading anti-doping protesters claim the test was introduced to detect recombinant EPO (erythropoietin), and Copycat versions of the drug are widely available and are often undetectable.
