Lance Armstrong's claims that his use of performance-enhancing drugs during his cycling career made it a level playing field have been labelled "amazing" and "simply not true" by United States Anti-Doping Agency chief executive Travis Tygart.

The disgraced Texan, who was stripped of his seven Tour de France titles by the sport's world governing body the UCI last year, admitted doping in an interview with Oprah Winfrey earlier this month, saying: "That's like saying we have to have air in our tyres or water in our bottles. It was part of the job."

He added: "I looked up the definition of cheating and the definition is 'to gain an advantage on a rival or foe'. I did not view it that way. I viewed it as a level playing field."

In an interview to be aired in full at midnight tonight, Tygart told CBS' 60 Minutes programme: "It's amazing. You could go to almost any kindergarten in this country or frankly around the world and find kids playing tag or four square and ask them what cheating is.

"Every one of them will tell you (cheating) is breaking the rules of the game.

"No real athlete has to look up the definition of cheating. It's offensive to clean athletes who are out there working hard to play by the rules that apply to their sport."

Asked if the 41-year-old was right to view it as a level playing field, Tygart - whose organisation prompted UCI's action by claiming Armstrong and his US Postal team had run "the most sophisticated, professionalised and successful doping programme that sport has ever seen" - replied: "It's just simply not true.

"The access they had to inside information - to how the tests work, what tests went in place at what time, special access to the laboratory... he was on an entirely different playing field to all the other athletes - even if you assume all the other athletes had access to some doping products."