Tokyo 2020 sponsor Toyota won't run any Olympic TV ads during the Games or send executives to the opening ceremony, an official told AFP on Monday, as the coronavirus-hit event struggles for public support.

The world's biggest automaker is a major sponsor of Tokyo 2020, which has faced persistent opposition in Japan and will take place mostly without spectators as Covid-19 cases rise in the capital.

"Toyota officials will not attend the opening ceremony, and the chief reason behind it is there will be no spectators," Toyota spokeswoman Shiori Hashimoto told AFP.

Fewer than 1,000 Olympic officials and VIPs including sponsors will be allowed to watch the opening ceremony on Friday, according to Japanese media.

Hashimoto denied reports by multiple local media outlets that Toyota had cancelled plans to air TV adverts related to the Olympics in Japan, however.

"There was never a plan to air Olympics-related commercials for promotional purposes in Japan in the first place," she said.

Around 60 Japanese companies have ploughed a record $3.3 billion into Tokyo 2020, while top sponsors like Toyota account for $500 million more.

Their hopes of a marketing bonanza have been tempered by the spectator ban, although they can still expect exposure from international broadcasters.

The pandemic-postponed Games are largely unpopular with the Japanese public
The pandemic-postponed Games are largely unpopular with the Japanese public AFP / Charly TRIBALLEAU

Earlier Monday, Toyota's operating officer Jun Nagata told reporters it was becoming more difficult for the Olympics to strike a positive chord with the Japanese public.

"It is turning into an Olympics that cannot get understanding (from the public) in various ways," Nagata told Japanese media, in comments that were confirmed by Hashimoto.

It comes after the first athletes tested positive for the virus in the Olympic Village, raising fears of a cluster just days ahead of the opening ceremony.

At least 58 cases linked to the Games have been discovered this month, including four athletes.

A weekend poll in the Asahi Shimbun newspaper found that 55 percent of voters were opposed to holding the Olympics this summer, with 33 percent in favour.

Prime Minister Yoshihide Suga has pledged that the Games will be "safe and secure", but 68 percent of respondents in the Asahi poll said they thought that was impossible.

Tokyo 2020 spokesman Masa Takaya said he was not aware of the reports about the Toyota adverts, but insisted sponsors remained supportive.

"I know those partners and sponsors must have been struggling to support Tokyo 2020," he told reporters on Monday.

"Of course, considering the public sentiment... there must be a decision by each company in terms of how they should be able to disseminate, how they should be able to convey their messages to the public audiences."