TOKYO (BLOOMBERG) - While Dr Shigeru Omi may invite comparisons to Dr Anthony Fauci, Japan's top Covid-19 adviser has shown little of his American counterpart's flair for challenging politicians.

That is, until he started suggesting banning spectators from the Tokyo Olympics.

Dr Omi, the government's top adviser on Covid-19, is a mild-mannered 72-year-old public health expert often seen by Prime Minister Yoshihide Suga's side.

But his concern over the health risks seems to have prompted him to question the government's plans to allow domestic fans at the Olympics.

Any tensions between Dr Omi and Mr Suga could be on display on Thursday (June 17), when the Premier holds a news conference at 7pm after his government recommended ending a virus state of emergency for Tokyo and other regions on June 20 as planned.

Dr Omi has generally been at his side for previous press conferences on virus measures.

Dr Omi appeared to open a gap with Mr Suga, who has pressed ahead with holding the Olympics as planned, when he told a parliamentary committee on June 2 that "it's not normal" to be staging the global sports spectacle in the middle of a pandemic.

The organisers needed to make a stronger case for holding the event in order to gain people's necessary cooperation, he said.

"Why on earth are we doing this in the current circumstances?" Dr Omi said. "The purpose hasn't quite been made clear."

Such public questioning of the official position is unusual in Japan's hierarchical political culture and has boosted his already considerable public profile.

Like Dr Fauci when Mr Donald Trump was US president, Dr Omi's views have given voice to a segment of the Japanese public dismayed with the government's direction.

While the tenor is far lower than the fever pitch of American politics, Dr Omi's remarks have also invited a swift backlash, just as Dr Fauci is now a lightning rod figure in the prolonged debate over virus policy and health measures in the US.

Former Internal Affairs Minister Heizo Takenaka told a TV talk show that Dr Omi had exceeded his authority with the remarks.

Now Dr Omi and other experts are set to release a proposal on the Olympics, which Health Minister Norihisa Tamura has already indicated he won't be treating as official advice.

Dr Omi told reporters on Wednesday the general outline of his report had been decided, declining to elaborate before its release.

Public broadcaster NHK said the report says holding the games without fans would be the least risky option.

The news made for its most-shared story on its website on Thursday morning.

"Japan doesn't have a system where members of the establishment air their own independent views," said Mr Tsuneo Watanabe, a senior research fellow at the Sasakawa Peace Foundation in Tokyo.

"It doesn't go as far as North Korea or China, but everyone's very cautious. The government doesn't choose people who will express different opinions."

Olympic questions

Dr Omi has said the greatest danger lay not within the athletes' bubble, but among the fans who would travel to Tokyo, creating more opportunities for the virus to spread.

Organisers announced in March that overseas spectators wouldn't be allowed.

The government is backing a 10,000-person limit on public events, which could be applied to the Olympics.

A decision on spectators was expected later this month, government spokesman Katsunobu Kato said Wednesday.

Domestic media have reported that some spectators are likely to be allowed at venues, although the decision may not be made public until after the state of emergency in Tokyo ends.

Organisers for the Tokyo Olympics and Paralympics plan to halt selling any more tickets to the events, Kyodo News reported on Thursday, citing an unnamed official with knowledge of the move.

In a survey by public broadcaster NHK published this week, 29 per cent of respondents said the Olympics should be held without spectators and 31 per cent said it should be cancelled.

About 32 per cent said it should be held with limited numbers of spectators.

Mr Suga has repeatedly said the Olympics can be held safely, despite waves of virus infections and a vaccine roll-out that lags other wealthy nations.

He faces a party leadership vote in September and if there are major problems with the Olympics under his watch, he could join a long list of short-serving Japanese prime ministers.

At the Group of Seven (G-7) leaders meeting in Cornwall, UK, over the weekend, Mr Suga's debut at a multilateral in-person summit, the Premier won the support of US President Joe Biden and other leaders for the Olympics.

A rift with the administration is an unfamiliar situation for Dr Omi, previously more likely to be criticised for tailoring his opinions to suit the government.

In an article on his alma mater's website, he says he never felt like taking part in the left-wing student demonstrations raging in Tokyo when he entered the elite Keio University in the 1960s.

Dropping out of a law course in favour of a medical degree at the then newly formed Jichi Medical University, Dr Omi went on to earn a doctorate on the Hepatitis B virus, and eventually landed the job of World Health Organisation director for the Western Pacific.

A fluent English-speaker, he was so plugged into the political system that he was in 2006 nominated by the Japanese government to be WHO director-general.

The pandemic may be prompting him to set aside his diplomatic skills.

"If they hold it, I want the Olympic and Paralympic Organising Committee to reduce it in scale as far as possible, and strengthen the management system as much as they can," Dr Omi told lawmakers on June 2.