The International Cycling Union has rejected allegations that Lance Armstrong failed a drugs test 10 years ago and that the sport's ruling body covered it up.
The UCI says allegations from Armstrong's former team mate Tyler Hamilton on the U.S. television progamme "60 Minutes" are completely unfounded.
Hamilton confessed to cheating and said doping was widespread, claiming Armstrong also escaped punishment after being caught.
But the UCI says it has never altered or hidden the results of a positive test.
Armstrong has repeatedly had to fend off doping accusations, despite always maintaining his innocence and never failing a test.
Another former team mate, Floyd Landis has also accused Armstrong of testing positive during the 2001 Tour of Switzerland but escaping punishment.
The UCI began legal action against Landis this month.