Olympic star Marion Jones (search) injected herself in the leg with human growth hormone while BALCO head Victor Conte watched, he told ABC News in an interview for "20/20," to be aired Friday.

Jones also was given other performance-enhancing drugs by Conte, one of four men indicted in an alleged steroid-distribution ring.

Jones' attorneys denied that she ever used performance-enhancing drugs.

In excerpts released by the network of the interview to be broadcast Friday night, Conte said he started supplying Jones with performance-enhancing drugs in the weeks leading up to the 2000 Olympics, where Jones won five medals.

Conte said he gave her a substance called "the clear," which was later determined to be THG, EPO and insulin. He also showed her how to inject hGH into her leg.

"After I instructed her how to do it and dialed it up, she did the injection with me sitting right there next to her ... right in front of me," he told ABC.

Conte told ESPN the Magazine for an upcoming issue that Jones wasn't nervous about injecting herself.

"There was a lot she needed to know, like how to assemble it, how to get the air bubbles out of the cartridge so she didn't inject air, and how to inject herself ...," he said. "She was wearing stretch bicycle shorts, and she pulled up the spandex above her right thigh. She dialed up the cartridge injector to deliver 4.5 units of growth hormone. I was sitting about a foot away from her as she injected the growth hormone into her quadricep."

Jones, who is under investigation for steroid use by the U.S. Anti-Doping Agency (search), has denied using any performance-enhancing drugs and passed a lie detector test arranged by her attorneys in June.

"Mr. Conte's statements have been wildly contradictory, while Marion Jones has steadfastly maintained her position throughout: She has never, ever used performance-enhancing drugs," said her attorney, Rich Nichols. "... Mr. Conte is simply not credible. We challenge him to submit to the same lie detector procedure that Marion Jones passed."

Phone calls and e-mails to Conte's attorney, Robert Holley, weren't immediately returned.

Jones, who failed to win a medal at this year's Olympics, has never failed a drug test, but Conte said no accurate tests existed for the substances he gave her during the approximately 13 months he worked with her.

"I know that she was tested many, many times from the timeframe that I worked with her ... And she obviously passed all those drug tests, including the ones at the Olympic Games," he said. "So as I told you earlier ... it's like taking candy from a baby."

International Olympic Committee (search) president Jacques Rogge said he was aware of Conte's allegations.

"I hope the truth will emerge," he said. "We want the truth. We want to know what happened and the more we know the better."

Rogge spoke to the AP in Dubrovnik, Croatia, where he is attending a meeting of the European Olympic Committees.

Conte also told ESPN the Magazine that a new drug, which he dubs "the clear III," is currently in circulation.

Conte was indicted in February by the grand jury investigating the Bay Area Laboratory Co-Operative (search). Conte, BALCO vice president James Valente, Barry Bonds' (search) personal trainer Greg Anderson and track coach Remi Korchemny all have pleaded not guilty to the charges.

Conte also said he developed a plan to use drugs to help Tim Montgomery (search), the father of Jones' baby, break the world record in the 100 meters in 2002. Montgomery's attorney, Howard Jacobs, declined to comment on the charges.

Conte also admitted to giving steroids to Anderson, but did not know whether Anderson gave any of them to Bonds or other baseball players.