Disgraced cyclist Lance Armstrong attempted to donate around $250,000 to the US Anti-Doping Agency (USADA), the head of the agency says in a "60 Minutes" episode which airs on US television Wednesday.

USADA chief executive Travis Tygart said he was bowled over by the "totally inappropriate" offer from one of Armstrong's representatives in 2004 which he immediately turned down.

"I was stunned," Tygart said in the interview. "It was a clear conflict of interest for USADA. We had no hesitation in rejecting that offer."

Asked if the offer was in the range of $250,000, Tygart told the interviewer, "It was in that ballpark."

The television programme distributed Tygart's comments in a news release on Tuesday ahead of Wednesday night's airing of the interview.

Tygart, who described Armstrong's heavy-handed tactics as being similar to the "Mafia", denounced a $100,000 donation Armstrong made previously to the International Cycling Union (UCI).

Armstrong's lawyer, Tim Herman, told USA Today Tuesday that there was never a donation attempt from the cyclist.

"No truth to that story," Herman told the newspaper. "First Lance heard of it was today. He never made any such contribution or suggestion."

USADA stripped the American of his seven Tour de France titles and slapped him with a lifetime ban in October after releasing a damning report that concluded Armstrong helped orchestrate the most sophisticated doping programme in the history of the sport.

The UCI effectively erased Armstrong from the cycling history books when it decided not to appeal sanctions imposed on Armstrong by USADA.

The massive report by USADA included hundreds of pages of eyewitness testimony, emails, financial records and laboratory analysis of blood samples.

"We have an obligation to clean athletes and the future of the sport. This was a fight for the soul of the sport," Tygart said.

US federal officials investigated Armstrong and his cycling team for two years but failed to charge him.

The decision not to charge Armstrong stunned Tygart. He was also shocked when the US Justice Department refused to share the results of their probe with him.

Asked why he thought the Justice Department refused to bring charges, Tygart said, "It's a good question and one that if you finally answer, let me know."

Tygart said Armstrong and his secretive inner circle of doctors, coaches and cyclists acted like "Mafia" the way they intimidated cyclists into using performance-enhancing drugs.

"It is our job ... to protect clean athletes. There are victims of doping," Tygart said.