World record holder Haile Gebrselassie has withdrawn from the Olympic marathon.

The Ethiopian runner, who suffers from asthma, said he would not compete because fears Beijing's air pollution would damage his health.

Gebrselassie said: "The pollution in China is a threat to my health and it would be difficult for me to run 42km in my current condition".

"But I am not pulling out of the Olympic event in Beijing all together. I plan to participate in the 10,000."

International Olympic Committee (IOC) chief Jacques Rogge said last year that events such as the marathon could be rescheduled if contingency measures did not have the desired effect.

The IOC would not comment on Gebrselassie's decision but a spokesperson said the committee was satisfied with pollution levels taken during test events.

Gebrselassie called on China to deal with the problem, saying that pollution "would be a hazard to athletes, seriously affecting their performances."

Rogge said last November in New York that a monitoring system would be set up in Beijing to gauge whether air pollution warranted delaying events, saying events that involve endurance could be delayed for a few hours or until another day.

"During a marathon for more than two hours, riding a bicycle race for five to six hours, that could be a danger hazard and then we would postpone the race," he said at the time.

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