A former teammate of Lance Armstrong has told CBS News that he used performance-enhancing drugs with the seven-time Tour de France winner to cheat in cycling races, including the Tour de France.

Tyler Hamilton says Armstrong took a blood-booster called EPO in the 1999 Tour and before the race in 2000 and 2001. Armstrong won the race every year from 1999 to 2005.

Armstrong has steadfastly denied doping and has never failed a drug test.

Federal investigators are probing whether Armstrong and his former U.S. Postal team engaged in a systematic doping program, which he denies.