The Tokyo metropolitan government on Sunday reported 239 new cases of coronavirus infection, as the country maintained its guard amid a spike in infections in urban areas and growing fears that the medical system may be under strain.

The latest figure came a day after Tokyo reported 295 new cases, with a single-day record of 366 confirmed last Thursday. It was the sixth straight day that the figure had surpassed 200, bringing the cumulative total for the capital to 11,214.

The daily figures announced by the metropolitan government reflect the most recent totals reported by health authorities and medical institutions in the capital.

Across Japan, 825 new infections were reported on Sunday, bringing the nationwide total to over 31,300, including around 700 cases from the Diamond Princess cruise ship quarantined in Yokohama in February.

Tokyo has seen single-day new infections in the triple digits on all but two days in July. The figure topped 300 for the first time recently and has often exceeded 200, while the cumulative total of coronavirus cases in Tokyo topped 10,000 on Wednesday.

People in their 20s and 30s accounted for around 60 percent of the new infections, while there were 35 cases among those in their 60s and above, showing signs that the virus is gradually spreading across the population.

Those with severe symptoms increased to 18 with two additional cases among previously confirmed patients whose conditions had deteriorated, according to the metropolitan government.

Of the total, 144 were infected via unknown routes.

At a press conference, economic revitalization minister Yasutoshi Nishimura, who is in charge of the coronavirus response, reiterated his call for businesses to thoroughly implement anti-virus measures, such as refraining from large gatherings and promoting telework.

Tokyo Gov. Yuriko Koike had urged residents to avoid nonessential outings during the four-day holiday from last Thursday, having raised the pandemic alert to the highest of four levels, indicating "infections are spreading."

There is widespread concern over a resurgence of infections as other urban areas have also seen sharp rises in confirmed cases since a nationwide state of emergency was fully lifted in late May. Worries over a worsening of the outbreak were further stirred by a central government subsidy campaign to spur domestic travel that was launched before the four-day holiday.

Osaka Prefecture in western Japan reported 141 new cases, its second-highest daily figure after a record 149 cases on Friday. It was the fifth consecutive day for Osaka to see new cases in excess of 100.

Osaka has issued a yellow alert based on its own assessment standards for coronavirus infections since July 12.

Hyogo Prefecture, west of Osaka, confirmed a single-day record of 49 cases, while in Aichi Prefecture, central Japan, 80 new infections were confirmed. In Fukuoka Prefecture, southwestern Japan, a daily record high of 90 new cases were confirmed.

Despite the growing number of infections, Prime Minister Shinzo Abe has said the current situation does not warrant a re-imposition of a state of emergency.

The central government has said the spike in cases in Tokyo reflects the expansion of testing and the medical system in the country is not overburdened.