The Olympic host city Tokyo registered a record 3,177 new coronavirus cases on Wednesday, authorities announced, as rising infections put pressure on hospitals.

The rise will add to worries about the Games, which are taking place under unprecedented sanitary conditions, including a ban on spectators in most venues.

Nationwide, the number of new COVID-19 cases exceeded 9,000 for the first time, according to public broadcaster NHK's calculations.

Governors of three prefectures near Tokyo - Kanagawa, Chiba and Saitama - will ask the government on Thursday to declare states of emergency for their regions, Economy Minister Yasutoshi Nishimura, who leads Japan's COVID-19 response, told a parliamentary panel.

"I think we've entered a trend of sharp rises in cases, which I had feared the most," Kanagawa governor Yuji Kuroiwa told reporters.

Tokyo is under its fourth state of emergency, which is due to last through the Olympics, while the other three regions are implementing "quasi-emergency" measures.

Olympics organizers reported 16 new Games-related cases, for a total of 169 since July 1. Athletes, staff and media must all follow strict rules, including frequent testing, inside an "Olympic bubble."

Many Japanese are worried about a spread of infections from Games participants.

Japanese Prime Minister Yoshihide Suga on Tuesday urged people to stay home as much as possible and watch the Olympics on television. But senior opposition Constitutional Democratic Party lawmaker Jun Azumi said the government was being too optimistic.

"Unless it revises its view of the infection situation, after the Olympics end, there will be a serious national crisis affecting people's lives, beginning with a collapse of the medical system," the NHK public broadcaster quoted him as saying.

Japan has avoided the devastating outbreaks suffered by other countries such as India and the U.S., but its fifth wave of the pandemic is straining hospitals.