Tokyo 2020's organizing committee chief said on Friday she wants to allow thousands of Olympics spectators, setting up a possible clash with Japan's top medical adviser who media said is urging no crowds as the least risky option during a pandemic.

Japan is pushing ahead with hosting the Games which kick off on July 23 despite an ongoing fourth wave of Covid-19 infections and strong public opposition.

A final decision on domestic spectators will be made at a meeting to be held as early as Monday among Tokyo 2020 organizers, the International Olympic Committee, International Paralympic Committee, Japanese government and Tokyo Metropolitan government.

"I would like it to be held with spectators. I plan to head into the five-way meeting with that in mind," the Sankei newspaper quoted Tokyo 2020 head Seiko Hashimoto as saying in an interview published late on Thursday.

Speaking at the start of an experts meeting, Hashimoto said advice from Japan's top medical adviser, Shigeru Omi, had been received and would be discussed.

Media said Omi advised holding the Games without any spectators as the least risky option given the potential for another surge in Covid-19 infections.

Spectators from abroad are already banned from the sporting extravaganza.

Prime Minister Yoshihide Suga's government decided on Thursday to ease emergency coronavirus curbs in nine prefectures including Tokyo while keeping some "quasi-emergency" restrictions.

Health experts including Omi agreed earlier this week that the number of spectators at domestic events could be raised to 10,000, but only in areas where "quasi-emergency" measures, including limiting restaurant hours, have been lifted.

Tokyo is scheduled to be under the lesser restrictions until July 11 after the state of emergency - the third since April last year - expires for the capital on June 20.

The lifting of earlier emergencies have been followed by fresh increases in infections and strains on hospitals. Experts worry that will happen again as people start moving around more, especially since Japan's vaccination rate is low.

Omi, a former World Health Organization official has become increasing outspoken about the risks the event may spread the virus. Earlier this month, he told parliament it was "not normal" to hold the Games during a pandemic.

Hiroshi Nishiura, a Kyoto University professor and epidemiology adviser on the government's pandemic response who is a signatory to the Omi recommendations, said he believed cancelling the Games would be best, but that decision was for the government and organizers.

"If the epidemic situation worsened, no spectators and cancelling the Games in the middle (of the event) should be debated," he told Reuters.

Japan's public remains concerned about the risks. A survey by NHK public TV this month showed 32% favored a cap on spectators, 29% wanted no spectators and 31% wanted the Games to be cancelled.

Suga's handling of the Covid-19 outbreak has eroded his public support ahead of a general election that must be held by late October.

The same NHK survey put his disapproval rate at 45%, the highest since he took office last September, against a support rate of 37%.

Japanese media said earlier that Omi, who is set to give a news conference later on Friday, would also recommend that if spectators are allowed, restrictions should be tough, including limiting them to residents of the local area.

Omi would also likely say that if there are signs of a renewed surge, the government should not hesitate to declare another state of emergency and ban spectators, the Yomiuri newspaper said.

Japan has not experienced the explosive outbreaks seen elsewhere but a recent surge and initially slow vaccinations rollout prompted concerns about strains on the medical system.

The country has recorded more that 776,000 cases and over 14,200 deaths, while just 15% of its population has received at least one Covid-19 vaccination.

Hashimoto is scheduled to give her own news conference after Omi's to respond to the experts' proposals.