Lance Armstrong attempted to make a donation of "in excess of £150,000" to the US Anti Doping Agency shortly before his seventh Tour de France title, according to Travis Tygart, the organisation's chief executive.
"I was stunned," Tygart told CBS News. "It was a clear conflict of interest. We had no hesitation in rejecting that offer."
In August, Armstrong was stripped of his titles and banned from cycling after declining to contest doping charges against him.
His first interview since the ban is due to air on Oprey Winfrey's TV network next week.