Two athletes, including a Dutch tennis player, and 12 security staff for the Games have tested positive for the coronavirus, Jiji news agency reported on Tuesday.
Tokyo's 2,848 COVID-19 infections on Tuesday were the Olympic host city's highest since the pandemic began, officials said, as media reported that authorities had asked hospitals to prepare more beds for patients as the Delta variant drives the surge.
The rise in cases threatens to further erode support for Prime Minister Yoshihide Suga, whose ratings have slid to their lowest level since he took office last September, in large part because of his haphazard handling of the pandemic.
It also spells trouble for the Olympics, as many Japanese fear the influx of athletes and officials for the event could add to the surge. About 31% in a survey by the Nikkei daily on Monday said the Games should be cancelled or postponed again.
"Refrain from going out unnecessarily and I want you to watch the Olympics and Paralympics on TV," said Suga addresing the citizens after a meeting of ministers overseeing the coronavirus response convened.
"As we have seen a decline in the flow of the people, there is no such option," said Suga, when asked whether there is an option to cancel the Olympics.
Japan has avoided the devastating outbreaks suffered by other nations such as India, Indonesia and the United States, but the fifth wave of the pandemic fuelled by the Delta variant is piling pressure on Tokyo's hospitals.
As Delta has spread, the number of severe COVID-19 cases in the city over the last month roughly doubled to 78 as of Monday, government data showed. Coronavirus hospitalisations have also jumped at a similar clip, reaching 2,717.
By Sunday, only 20.8% of the Japanese capital's 12,635 COVID-19 patients had been able to obtain hospital treatment, the data showed. A government advisory panel says that if the ratio falls below the threshold of 25%, a state of emergency should be triggered.