Jones shock at result

Jones added she had requested the testing of her second or 'B' sample be dealt with quickly.

"I was shocked when I was informed about the positive 'A' sample," Jones said in the statement issued by her Los Angeles-area attorney Howard Jacobs.

"I have requested that the testing of my 'B' sample be expedited and done as soon as possible.

"I would also like to note that only my lawyers have the authority to speak on my behalf in this matter, and I will have no further comment until the results of the 'B' sample are released."

The comments were the first by Jones since sources said last Friday she had tested positive for the banned blood-boosting drug erythropoietin (EPO) at the U.S. championships in Indianapolis in June.

Jones, 30, has repeatedly denied taking performance-enhancing substances and had never previously failed a doping test.

"Marion Jones has always been clear, she has never taken performance-enhancing substances, not now, not ever," Jones's general counsel Rich Nichols said in a statement last Friday.

Jones had been under scrutiny by the U.S. Anti-Doping Agency (USADA) in connection with the BALCO laboratory doping scandal but has never been charged with a doping offence.

Her statement did not name the substance for which her 'A' sample was positive.

If her 'B' sample is positive, she faces a two-year ban from the sport under anti-doping rules.

Jones won five Olympic medals at the 2000 Sydney Games, including golds in the 100 and 200 metres and 4x400 metres relay.

She dominated sprinting in the late 1990s and early this decade while coached by Trevor Graham, who is currently under investigation by the International Association of Athletics Federations (IAAF) and USADA.

She had performed poorly since having a son with disgraced former 100 metres world record holder Tim Montgomery in 2003, but made a comeback this year.

Jones won the U.S. 100 metres championship in 11.10 seconds on June 23 and was first in several races in Europe this season.

She has three of the five fastest times in the world this year with a best of 10.91 seconds to rank second overall behind Jamaica's Sherone Simpson.

The statement by Jacobs, who has been hired to represent Jones in the case, confirmed the adverse finding was on her "A" sample was on June 23, the date of her 100 metres championship.

Jacobs has represented a number of U.S. athletes in anti-doping cases, including Jones's former partner Montgomery.

Montgomery was banned from the sport for two years based on evidence from the BALCO scandal and his 2002 world record time of 9.78 for the 100 metres was expunged.