Five-time Olympic medalist Marion Jones failed an initial doping test at the U.S. track and field championships where she won the 100 meters in June, people familiar with the results told The Associated Press.

Jones' "A" sample tested positive for the banned performance enhancer EPO at the event in Indianapolis, one source told the AP on condition of anonymity because the official results are not yet public.

If a second, or "B" sample, also tests positive, she would face a minimum two-year ban from the sport.

Erythropoietin, also known as EPO, is a banned performance-enhancer that can boost endurance. The result was first reported Friday on the Web site of The Washington Post, which also cited sources it did not identify.

The 30-year-old Jones withdrew from the Weltklasse Golden League meet on Friday, citing "personal reasons." Meet director Hans Jeorg Wirz said Jones received a morning telephone call from the United States that prompted her decision. No further details were given.

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Her coach, Steve Riddick, told the AP in a telephone conversation that it was the first he had heard of the positive test.

Jones is the third elite U.S. athlete to fail a doping test this year. U.S. cyclist Floyd Landis tested positive for elevated testosterone during the Tour de France; sprinter Justin Gatlin, a three-time Olympic medalist who shares the world record in the 100 meters, tested positive for a steroid in April.

Jones made a triumphant return to her sport's center stage by winning the 100 meters at the U.S. track and field championships June 23. It was her 14th U.S. championship but first sprint title since 2002.

She withdrew from the 200 meters just before the preliminaries, settling for the 100-meter title she won the previous night. She warmed up, but her agent, Charles Wells, said she decided her legs were too tired after running three rounds of the 100.

Jones raced five times in Europe this season, winning the 100 meters in Paris and Lausanne. She had been set to race in Zurich for the first time in two years after having been snubbed by the meet for her connection to the Bay Area Laboratory Co-Operative steroid scandal.

She was not invited to this year's Golden League final in Berlin on Sept. 3 because of links to former coach Trevor Graham, who is under investigation by track and field's ruling body and the U.S. Anti-Doping Agency. Other athletes who trained under Graham also were not invited.

Graham is the coach of Olympic and world 100-meter champion Gatlin, who faces a lifetime ban for his failed drug test. Several other athletes coached by Graham have been suspended for doping.

Jones is no longer coached by Graham, and works with Riddick. She has been dogged by doping allegations but had never failed a test before the U.S. championships and has repeatedly denied using performance-enhancing drugs.

Since winning three gold medals at the 2000 Games, the 30-year-old star has struggled. Her career best of 10.65 seconds in the 100 was in 1998. Her time of 10.91 at the Golden Gala meet in Rome last month was her fastest race in four years.

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