US sprinter Marion Jones failed a drug test at the national athletics championships in Indianpolis in June, the Washington Post reported on its Web site on Friday.
Quoting "sources with knowledge of the test results," the newspaper said that the five-time Olympic medalist had tested positive for the blood booster erythropoietin (EPO), although the result remained unconfirmed pending analysis of the "B" sample.
USA Track and Field (USAATF) declined to comment on the report, which also appeared in other US news media.
"We would refer any question about domestic doping cases to the US Anti-Doping Agency," said USATF spokesperson Jill Geer.
USADA could not immediately be reached, nor could Jones's agent Charles Wells.
The New York Times, in a story for yesterday's edition, said information on the positive "A" sample report had been provided by "people briefed on the results."
The Chicago Tribune said that according to a source familiar with the case the "B" sample is scheduled to be tested on Sept. 6.
Organizers of Friday's Golden League meeting in Switzerland said that Jones had withdrawn at the last minute citing "personal reasons."
Hansjorg Wirz, who is also head of the European Athletics Association, said Jones "received a phone call from the United States this morning and left for personal reasons."
"She was already on the plane when we got this information," Wirz said.