The Tokyo Olympics could be held without spectators depending on the COVID-19 situation in Japan, Prime Minister Yoshihide Suga reiterated Thursday amid growing concern the games in three weeks' time may trigger a surge in infections.

The remarks came as Suga appeared to have no choice but to extend a quasi-state of emergency covering the capital and three adjacent prefectures that is set to expire on July 11.

"I've said before there is a possibility of there being no spectators," Suga told reporters. "In any case, we will act with the safety and security of the Japanese people as our top priority."

The organizers of the Olympics, due to begin July 23, decided last month to fill venues up to 50 percent of capacity with an upper limit of 10,000 people.

But infections in Tokyo have climbed since a state of emergency was lifted last month, fueling uncertainty over whether it is possible to stage the games with that many fans.

The Tokyo metropolitan government reported 673 new COVID-19 cases on Thursday, up from 570 a week earlier, marking 12 straight days of week-on-week rises. The capital's daily count topped 700 on Wednesday for the first time since May 26.

Health experts have warned that at the current pace the daily figure could balloon to 3,000 in August.

Suga said any new decision on how to handle local fans at venues will be made by consensus among the five organizing bodies of the Tokyo Games -- which are the central and metropolitan governments, the Japanese organizing committee, the International Olympic Committee and the International Paralympic Committee.

They already decided in March to bar overseas spectators.

The 10,000-person attendance cap is contingent on the capital and other prefectures where the Olympics will be held exiting the quasi-state of emergency before the opening of the games.

Under the quasi-state of emergency, spectators are restricted to 50 percent of venue capacity with an upper limit of 5,000 people, a rule government officials have said may apply to the Olympics if an extension is deemed necessary.

In anticipation of such a scenario, the organizers are considering delaying the planned announcement next Tuesday of fresh lottery results for venue tickets, according to a government official with knowledge of the matter.

But reworking the lottery to accommodate a lower attendance cap "would be no easy feat," said a senior official at the prime minister's office, adding if the quasi-state of emergency is extended "we should just accept there won't be spectators."

A total of 10 prefectures are currently under a quasi-state of emergency, which entails restrictions on business activity including asking restaurants to stop serving alcohol at 7 p.m. and close by 8 p.m.

The central government is considering an extension for Tokyo and neighboring Chiba, Saitama and Kanagawa prefectures, according to sources with knowledge of the matter.

Many in Japan remain worried about having fans at the Summer Games, with about 40 percent of respondents in a Kyodo News poll last month saying the stands should remain empty.

Infectious disease experts including Suga's top COVID-19 adviser, Shigeru Omi, have also said holding the games without spectators is the "safest option."

Suga's remarks on Thursday came in response to a question about comments made by the leader of Komeito, the ruling Liberal Democratic Party's junior coalition partner, who said holding the Olympics without fans in attendance should remain an option.

"I've said we need to be on the lookout for a rebound in infections, and that's exactly what we are seeing now," Natsuo Yamaguchi told reporters. "I hope the government will remain open to the possibility of there being no spectators and inform the public of any decisions in a timely manner."

Meanwhile, athletes and staff participating in the Olympics have begun arriving en masse in Japan and heading to training camps.

More than 100 people touched down on Thursday, according to the Cabinet Secretariat, including the German boxing and boat racing teams, the Irish boxing team and the Australian soccer squad. Around 400 are slated to arrive by Sunday.

The central government has imposed stricter COVID-19 rules on athletes and staff from abroad after a member of the Ugandan delegation tested positive upon arrival at Narita airport near Tokyo but the rest of the team was allowed to continue by chartered bus to Osaka Prefecture, where another member was also found to be infected.

Under the new protocols, people who may have been in close contact with someone with a positive test must self-isolate, with offenders facing disqualification from competition, fines and even deportation.

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No spectators at Tokyo Olympics should remain option: Komeito chief