Three months before the 2006 Winter Games, at a time when drug testers are usually unveiling new tests to catch cheaters, the World Anti-Doping Agency is grappling with a spate of recent challenges to its five-year old EPO test that threaten the test's credibility.

The directors of the more than 30 labs that do analysis for WADA were summoned to Paris on Wednesday for an emergency three-day meeting to discuss the test for EPO, also known as erythropoietin, a banned blood-boosting drug useful to athletes in endurance sports. But even as criticism of the test mounted, WADA officials said they had not lost confidence in it.

"There is no issue about the reliability of the test per se," WADA Chair Dick Pound said in an e-mail. "The only point is to make sure all the labs are able to interpret the results properly. In the past ,and I assume it will be repeated, we have suggested that if a lab director is not certain about a positive EPO test, it should be referred to one that has experience. I expect we will also remind them that the next phase of attacks on anti-doping activity will probably be directed at the labs, so they should be sure to follow best practices, et cetera. "

The meeting comes after a summer in which EPO positives were overturned in the cases of three triathletes, including Belgium's Rutger Beke, who had already served an 18-month suspension before his positive was invalidated by a Belgian court in August. Kenyan-born distance runner Bernard Lagat, now a U.S. citizen, also tested positive for EPO in 2003, but the B sample did not confirm the A and he was fully exonerated.

A number of triathlon publications reported that Spanish triathlete Virginia Berasategui and her training partner, Iban Rodriguez, had EPO positives overturned in September. A WADA spokesperson said she could not immediately confirm those results but Berasategui detailed her experience on her Web site, calling it a "nightmare."

But no case has garnered the attention of cyclist Lance Armstrong, who reportedly tested positive for EPO when samples taken in 1999 were analyzed for research purposes by a French lab this summer. Armstrong has vehemently denied the reports, but some sports officials have called for an investigation into the charges.

The current test, patented by French scientists and adopted shortly before the 2000 Summer Games in Sydney, claims to distinguish between naturally produced EPO and artificial EPO. Critics, though, say that naturally produced EPO or other proteins can sometimes look like artificial EPO, possibly creating false positives and even a 2003 report commissioned by WADA on the test cited shortcomings related to the test's complexity. Beke's lawyers showed that his body produced certain proteins when he exercised heavily that created the appearance of a positive test.

"WADA doesn't want to address any deficiencies in any of its tests, but if they don't change the test, given the way it's done currently . . . I think it's going to be an issue in probably every EPO case that comes up from now on," said Los Angeles attorney Howard Jacobs, who is appealing EPO bans for two U.S. distance runners.

WADA has acknowledged the issue of the confusion between naturally and artificially produced EPO, but said its labs had been fully informed of a new interpretation criteria designed to ensure that no false positives were reported. The organization said that the former interpretation criteria were less discriminate and would not have yielded positive results.

"Of course WADA can't back down," said one European sport official, who requested anonymity. "How can they back down on a test they've used to ban people for years? If they come out and say, 'Our test has got flaws,' how many millions are people going to sue for?"