By STEPHEN WILSON -- Associated Press
 RIO DE JANEIRO, Brazil (AP) -- Chances remain 50-50 that a test for the banned drug EPO will be ready in time for the Sydney Games, a top International Olympic Committee official said Thursday.

 Jacques Rogge, vice chairman of the IOC medical commission, denied reports in Europe that he said it was "virtually certain" the test would be introduced at the Sept. 15-Oct. 1 games.

 "I'm almost certain we will have a test in the future. I hope it will be for Sydney. I dearly hope so," Rogge said. "But I still say it's a 50-50 chance for the Sydney Games."

 EPO, or erythropoietin, is a hormone that boosts the production of oxygen-rich red blood cells in the body. Injected in synthetic form, EPO is believed to be widely used by athletes in cycling, long-distance running and other endurance sports.

 Critics have accused the IOC of dragging its feet in finding a reliable EPO test. But Rogge said the IOC will do everything possible to fast-track the process once a test is scientifically validated.

 The validation process involves publication in an international scientific magazine, peer review, backup testing and legal review.

 "Everything is in place," Rogge said. "It doesn't depend any more on the IOC. It depends on the international scientific community. They will decide, not us. ... While we want to track down the cheats, it's better to have five cheats go unpunished rather than one athlete punished unfairly."

 Earlier this week, researchers at a French laboratory reported developing a urine test for EPO and that it could be used at next month's Tour de France. Australian researchers say they have produced a blood test for EPO.

 The IOC could introduce one or both tests in Sydney, Rogge said.

 Even if an EPO test is used in Sydney, Rogge acknowledged that other banned drugs -- including human growth hormone and IGF-1 -- remain undetectable.

 "Finding the EPO test will not be the end of the road," he said. "It might be only the beginning."

 Meanwhile, Rogge said the IOC executive board approved requests by the modern pentathlon and cycling federations to carry out pre-competition blood tests in Sydney.

 These tests measure the level of red blood cells and are officially considered health checks, not doping controls. Any athlete testing above the permitted level is pulled out of the competition.

 Rogge also announced that the Australian government has agreed to allow independent observers to monitor drug-testing by the Australian Sports Drug Agency. The agency is carrying out tests on Australian and foreign athletes training for the Sydney Games.

 In a bid to remove public suspicion of coverups, the IOC announced last month that observers would monitor all stages of the committee's drug-testing procedures during the games. Rogge said the observers would number around six.

 On another issue, Rogge said the IOC is investigating the use of hyperbaric chambers, which boost endurance by replicating high-altitude conditions. The chambers have become increasingly popular with athletes, who can sleep in them at home or at competition sites.

 Rogge said the IOC would move to prevent athletes from bringing oxygen equipment into the Olympic village in Sydney.