In an interview aired on Wednesday, the US Anti-Doping Agency chief described the sophistication of the Lance Armstrong doping scandal, which included the use of untraceable cellphones, makeup to hide needle marks and an offer of a $US250,000 donation from one of Armstrong's representatives to USADA in 2004.

An investigation into the scheme resulted in the disgraced American cyclist being stripped of his seven Tour de France titles and banned from the sport for life.

Tygart said Armstrong had been tipped off by Swiss drug testing laboratory director Martial Saugy about how to beat the erythropoietin (EPO) test in 2002 after one of Armstrong's samples from the 2001 Tour of Switzerland was described as "suspicious."

"Saugy sat down next to me and said, 'Travis, in fact, there were samples from Lance Armstrong that indicated EPO use'," Tygart told CBS television's 60 Minutes Sports.

"As far as we are aware, (it is) totally inappropriate to bring in an athlete who had a suspicious test and explain to them how the test works."

The Swiss lab chief also told Tygart that the International Cycling Union (UCI) had asked him to hold an unprecedented meeting with Armstrong and his former manager Johan Bruyneel to explain the EPO testing process.

Tygart said six of Armstrong's samples taken during his first Tour de France win in 1999 eventually tested positive.

The samples were originally reported as negative but they were re-tested in 2005.

"All six were flaming positive," Tygart said.

The anti-doping chief said much of the information was obtained from the dozen former US Postal team members who were willing to testify against Armstrong, including Dave Zabriskie and George Hincapie.

He described a culture of fear among the cyclists who rode alongside Armstrong that was designed to keep the doping scheme secret and prevent anyone from blowing the whistle on the star athlete.

Hincapie told Tygart of a race in Spain in 2000 in which he texted a warning to Armstrong that he was about to be tested.

Armstrong "dropped out of the race to avoid testing," Tygart said.

"Our job is to follow the evidence. And we asked riders to come in and be truthful, nothing more, nothing less. And they were.

"We were disappointed (Armstrong) didn't come in and be part of the solution. It's one of the lowest days of this investigation, quite honestly."

The interview was conducted before the Armstrong, 41, announced he was going on the Oprah Winfrey television network later this month to tell his side of the story.

The famed talk show host said that a 90-minute special would address "years of accusations of cheating and charges of lying about the use of performance-enhancing drugs" throughout Armstrong's "storied cycling career."

Last week, The New York Times reported that Armstrong was considering publicly admitting that he used banned performance-enhancing drugs, in an apparent bid to return to competitive sport in marathons and triathlons. Armstrong has always vehemently denied doping.

Armstrong recently met with Tygart to explore the idea of a "pathway to redemption," according to CBS, but the anti-doping chief did not address the issue in the interview.

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

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

AFP