IOC chief warns events may be postponed at next year's China Games

The shock and embarrassing admission from Rogge, president of the International Olympic Committee, came just hours before Beijing was to celebrate the one-year mark in the countdown for next year's opening ceremony.

Gloomy outlook: heavy smog in Beijing spoils today's celebration party to mark the one-year countdown before the start of the 2008 Olympics

Beijing's choking industrial smog and clogged traffic have worried the IOC for some time but this is Rogge's strongest statement on the subject.

He said Beijing's air pollution could force the postponement of outdoor events at the Games.

The IOC president said: "Yes, this is an option. It would not be necessary for all sports, sports with short durations would not be a problem. But definitely the endurance sports like the cycling race where you have to compete for six hours, these are examples of competitions that might be postponed or delayed to another day."

Beijing Olympic organising officials refused to comment on Rogge's statement but Wang Junyan, director of Beijing Olympics cycling events, said: "Rogge's comment reminds us that we have to work harder to fix environmental problems."

Beijing has been blanketed for weeks by smog, limiting visibility to a few hundred yards.

Officials are hoping to control the weather during the Olympics. Meteorologists began tests last month, firing rockets to disperse rain clouds - a move to guarantee sunshine.

They've also fired rockets to induce rain to clean the air.