The widening fallout of the virus outbreak, which began in China in December and has already killed over 1,700 people, is damaging output and tourism in Japan, which is preparing to host the Games from late July.
A further spread of the virus in Japan, which last week reported its first fatality from the disease, could undermine growth and potentially push the country into recession, analysts say.
Organisers of the Tokyo Marathon, one of the world's biggest such races, said the 38,000 general participants who signed up for the March 1 race will not be allowed to compete.
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"We cannot continue to launch the event within the scale we originally anticipated," the organisers said in a statement.
Instead, the event will be limited to top-level competitors. A total of 176 elite runners and 30 elite wheelchair athletes are registered for the race.
The marathon is not the only international sporting event in Japan the virus has affected: The FIBA Asia Cup 2021 postponed a qualifying basketball game between Japan and China, originally scheduled to be held near Tokyo this week.
Citing "circumstances", the Imperial Household Agency said it would cancel Emperor Naruhito's public birthday address on Feb. 23, his first since his coronation last year. The event regularly attracts tens of thousands of people to the inner grounds of the Imperial Palace in the heart of Tokyo.

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The last time the emperor's birthday celebration was cancelled was 1996, amid a hostage crisis at the Japanese embassy in Peru.
An additional 99 people on a cruise ship docked in the Japanese port of Yokohama were confirmed on Monday to be infected with the virus, a day after 70 were confirmed to have the virus, bringing the total number of infections aboard the Diamond Princess to 454.
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