NEW YORK -- Tests show that some of the testosterone in Floyd Landis' system at the Tour de France was synthetic and not naturally produced by his body as he claimed, according to a newspaper report.

The French antidoping lab testing the American cyclist's samples determined that some of the hormone came from an external source, The New York Times reported on its Web site Monday night, citing a person at the International Cycling Union with knowledge of the result.

A confirmation of the result would undermine the defense that Landis has stood behind since he tested positive for an abnormally high ratio of testosterone to epitestosterone in one sample taken following the 17th stage of the Tour de France, where he staged a stirring comeback in the Alps to make up for a poor performance the day before.

The analysis of Landis' "B" sample is expected to take place Thursday through Saturday at the Chatenay-Malabry anti-doping lab outside Paris, International Cycling Union spokesman Enrico Carpani said Tuesday.

If the "B" sample is negative, Landis would be cleared. If it

is positive, which his lawyers expect, he could be stripped of his

Tour victory and banned for two years. Landis could become the

first Tour winner to lose the title in a doping case.

He will be given "due process" to defend himself before an

arbitration panel -- which could delay any possible penalties -- if

he continues to deny the allegations, UCI president Pat McQuaid

said.

"It could take weeks," McQuaid told The Associated Press by

telephone. If the test is confirmed, no penalties could be decided

"until the disciplinary process is completed."

It could take even longer if the case goes to the Court of

Arbitration for Sport.

McQuaid said Tuesday he had not seen the lab

findings and could not confirm the Times report, but the cycling body had asked the French lab to speed up its analysis.

McQuaid said the uncertainty was not good for the sport.

"The longer it goes until the 'B' sample is tested, the more

speculation, and the more denial and the more of everything that

goes on," he told The Associated Press during a telephone

interview.

Analysis of the B sample takes 2½ days, he said, and the lab

closes this weekend for August vacation.

Landis' lawyers in Spain filed an official request for the "B" test late Monday. But Carpani said the UCI had already filed its own request earlier Monday because of concerns about the case dragging on.

Landis' Swiss-based team, Phonak, wants the results as quickly

as possible.

"The sooner that's done, the better it will be for the team," Phonak team manager John Lelangue said. He declined to answer any other questions.

Looking and sounding defiant, Landis said Friday that his body's natural metabolism -- not doping of any kind -- caused the result and that he would undergo tests to prove it.

"We will explain to the world why this is not a doping case but a natural occurrence," Landis said at a news conference in Madrid, Spain.

But after determining that Landis' ratio of testosterone to epitestosterone was more than twice the limit of 4:1, the lab performed a carbon isotope ratio test on the first of Landis' two urine samples to determine whether it was natural or synthetic, the person, who The Times said works in the cycling union's antidoping department, told the newspaper.

If the "B" test is negative, Landis would be cleared. If it's positive, which Landis' lawyers say they expect, he could be stripped of his Tour victory and banned for two years. At that point, Landis could still choose to appeal the results.

Landis has been suspended by his team, Phonak, pending the result of his "B" sample.

But the result showing synthetic testosterone does not need to be confirmed with a second test, said Dr. Gary Wadler, a member of the World Anti-Doping Agency and a spokesman for the American College of Sports Medicine.

"The rules say that it is a violation, but if you can show that the athlete had no fault or no significant fault, there could be a mitigation of the sanction," Wadler told the Times. "No matter how it got there, the athlete has to show how it got into his or her body. It could have been sabotage or contaminated dietary supplements or something else, but they have to prove how the testosterone got there."

The Times said Landis was in New York on Monday night and could not be reached for comment.

Oscar Pereiro of Spain, who finished second overall in the Tour de France, would be declared the winner if Landis loses the Tour de France title. It would be the first time in the history of the Tour of France that the winner has been disqualified for doping.

Information from The Associated Press was used in this report.