SYDNEY, Australia - Chinese organizers have been reluctant to release the findings of air pollution tests conducted 12 months out from next year's Summer Games, medical advisers to Australia's Olympic team said Monday.

Chinese authorities took air quality readings at Beijing in August when a number of pollution-reduction measures were in place, including the removal of about 1.3 million of the city's three million cars from the road.

Australian sports officials have flagged Beijing's notorious smog as a major potential factor that could affect the performance of athletes at the 2008 Olympics.

Australian sports physician Dr. Ken Fitch questioned Chinese claims that the measures resulted in a 15-20 per cent reduction in air pollution.

"I find it difficult to see that level in reduction in pollution as claimed,'' Fitch told an Olympic health and medical forum in Sydney on Monday.

Fitch said outside analysts had made repeated requests for details of small particle and ozone levels -- crucial for asthma sufferers -- and associated data like how pollution varies through the day, but these had not been forthcoming.

"We've got to have the information before we can be as happy as we'd like to be,'' said Fitch, who has been associated with Australia's Olympic campaigns since Munich in 1972.

He hopes to get more details when he and other members of the IOC medical commission meet officials from the Beijing organizing committee, BOCOG, at Monaco late next week.

Micro-particles associated with air pollution can potentially trigger asthma attacks, and cause heart problems among athletes in endurance events like the marathon, triathlon, cycling road race and race walks.

As a precaution against possible high levels of air pollution, the Australian Olympic Committee is advising its athletes to arrive in Beijing as late as possible, around four or five days before competition, and to spend as much time as possible acclimatizing before the Games.

Fitch is confident that Beijing Olympic organizers will do everything possible to control pollution, including shutting down industry and keeping large numbers of vehicles off the road for the duration of the Games.

"The health of the athlete is paramount these days, and I'm confident that the Chinese will make a great effort to reduce pollution,'' he said. "This is a big thing for that country and they're not going to fall down on this issue, but we must keep the pressure on them.''

IOC president Jacques Rogge has already said events may be postponed if the pollution levels are too high.