The decision, made after Prime Minister Yoshihide Suga announced on Thursday a fourth state of emergency for the capital, all but robs the Games of their last hope for pomp and public spectacle.

Japanese Health Minister Norihisa Tamura said he felt sorry for athletes but that the decision was the right one.

"Please stay at home for this Olympics, and share that excitement with families at home," he told a news conference on Friday.

The Games are scheduled to run from July 23 to August 8, and opinion polls have consistently shown the Japanese public is worried about going ahead with them during a pandemic.

In a recent media survey, 35 per cent favoured no spectators, 26 per cent wanted some limits and 34 per cent wanted the Games cancelled or postponed. Spectators from overseas were banned months ago.

"We came to a conclusion that we were able to gain understanding from more people for hosting (the Olympics), if we held it without spectators, although it is unfortunate," Tokyo 2020 President Seiko Hashimoto said after the decision.

Sports ruling bodies including World Athletics, the International Hockey Federation (FIH) and swimming's world governing body FINA were understanding but expressed their disappointment at the decision.

World Athletics said athletes have become used to competing in stadiums that are not packed but would have loved to see "noisy fans" in Tokyo.

"This is disappointing for everyone," World Athletics said in a statement. "For the people of Tokyo and Japan, the chance to see the world's best athletes competing in the flesh is an opportunity that does not come around very often."

Once seen as a chance for Japan to showcase its recovery from prolonged stagnation and a devastating earthquake a decade ago, the event was delayed by the pandemic last year and has been hit by massive budget overruns.

Medical experts have said for weeks that having no spectators would be the least risky option, amid widespread public fears that an influx of tens of thousands of athletes and officials will fuel a fresh wave of infections.

Japan has not suffered the explosive outbreak seen elsewhere but has recorded over 800,000 cases and over 14,890 deaths. Tokyo reported 896 new infections on Thursday, the 19th straight day of week-on-week rises.

The Tokyo leg of the Olympic torch relay kicked off on Friday with a small ceremony in a nearly empty park. The relay will be kept off public streets and only small ceremonies with no public spectators will be held over the next two weeks

People will also be asked not to gather for events on public roads, such as the triathlon, though some venues outside the greater Tokyo metropolitan area will allow small numbers of spectators.

Australian Associated Press