Volunteers are the backbone of any Games, performing everything from guiding people to venues, translating and driving visitors around.

A significant drop in their numbers could be another hurdle for Tokyo 2020, already hit by an unprecedented year-long postponement and a lack of public support fuelled by concerns over the coronavirus pandemic.

Tokyo 2020 organisers said not all those volunteers who stepped down recently were quitting due to Mori's comments.

Surveys have shown volunteers repeatedly expressing concerns about the coronavirus.

The total number of volunteers recruited by Tokyo 2020 is 80,000 and organisers have said they don't expect running the Games will be affected, since the number quitting is only about one per cent of the total.

Another 30,000 volunteers have been recruited separately by the Tokyo Metropolitan Government, which was unable to immediately comment on how many have quit.

In addition, the postponement of the Games has affected some volunteers, who were in a position to help last year but aren't this year, due to job changes or other lifestyle changes, such as having to care for small children.

The Olympics are due to run from July 23 to August 8.

Meanwhile the Tokyo Olympic Organising Committee are asking spectators for the upcoming torch relay to support by clapping and will broadcast the event live to avoid gatherings.

The torch relay, which will begin on March 25, could be temporarily suspended over concerns about the coronavirus pandemic if big gatherings are spotted on streets during the event, Yukihiko Nunomura, senior executive at Tokyo 2020, told a media briefing.

"By any chance, if any dense gatherings happen on streets, torch relay can be stopped as we prioritise safety and security," Nunomura said.

Australian Associated Press