Triple Olympic champion Marion Jones admitted on Wednesday that she received a mineral supplement provided by BALCO, the firm at the center of a federal doping probe, but again denied taking any steroids.

After telling a news conference she had never used any product from the nutritional lab BALCO, she conceded that she had received BALCO's zinc supplement ZMA between 1999-2001.

The owner of BALCO, Victor Conte, and his deputy who heads the division selling ZMA, James Valente, have both been charged with distributing steroids.

"I never actually said that I took supplements from BALCO. I said my training team was seeking out a company who produced and made supplements. Beyond that I never said that I accepted nor took any supplements from BALCO," Jones said at San Francisco news conference aimed at clearing her name.

Just minutes later, Jones reversed herself and said she had received the legal supplement from BALCO.

"Actually ZMA was sent to me from BALCO, all right," she said. She added: "I began getting ZMA from BALCO, I have to say in 1999. And, like I said, I stopped taking ZMA from BALCO -- I still take it to this day from (nutrition products company) GNC -- from the beginning of 2001."

Jones, who has never failed a drug test, is under suspicion because of her relationship with BALCO, which has been linked to top athletes in track and field, baseball and football.

The U.S. Anti-Doping Agency (USADA) recently gave Jones documents stemming from the BALCO investigation they believe show steroid use, something Jones denied before the BALCO grand jury last year and again on Wednesday.

COMMON VITAMIN

ZMA is a legal supplement sold widely including in vitamin stores. On his firm's website, Conte says he developed ZMA and said his SNAC firm holds a registered trademark.

"Many 1988, 1992, 1996 and 2000 U.S. Olympic medallists achieved their success utilizing the ingredients in ZMA," the snac.com website reads.

Some top athletes, including baseball slugger Barry Bonds, have praised ZMA, as Jones once did in a fitness magazine. Bonds's personal trainer Greg Anderson is one of four people charged in the BALCO scandal.

"What I did say in that article is that I endorsed a product called ZMA," Jones said. "I admitted to taking ZMA and still take ZMA. I think it is a beneficial product."

Despite her continued denials of ever using steroids, Jones is facing questions because of the link to BALCO and Conte, a former bass guitarist and college drop out.

"My training team found Victor Conte and BALCO and that's how the relationship started," Jones said. "I have never accepted or received any prohibited substance from any company."

Jones also condemned USADA, the agency charged with screening out tainted athletes from the U.S. Olympic team.

"I am more than happy to answer every question but I'm not going to engage in USADA's secret kangaroo court," Jones said, in firm and sometimes emotional tones.

"I will answer their questions in a public forum open for entire world to see hear and evaluate.

"For a third time I will answer all of their questions, but I'm not going to answer them behind closed doors I'll answer them in public and in the light of day."

In a statement, the legal affairs director at USADA said a clean athlete had nothing to fear from scrutiny.

"If Ms Jones wants the truth to come out, then we share that goal," said Travis Tygart. "No athlete who has not engaged in doping behavior has any reason to fear, or otherwise avoid, the USADA process."