Tokyo Gov. Yuriko Koike said Sunday she might ask the central government to issue a fresh coronavirus state of emergency for the capital to deal with a recent spike in cases.

"Taking a proactive approach is indispensable in responding" to the spike, Koike said, as the capital reported 543 new COVID-19 cases the same day, surpassing 500 for the sixth consecutive day, with only three months left before the opening of the Tokyo Olympics.

"I have instructed senior metropolitan government officials to study countermeasures with a sense of urgency, while considering (the possible option of) requesting a state of emergency," the governor said.

If issued, it would be a third COVID-19 state of emergency for the capital, following the first one in place between April and May 2020 and the second one between January and March this year.

Meanwhile, Osaka Prefecture, the epicenter of the current resurgence seen as a fourth wave of infections in Japan, reported on Sunday 1,220 new cases, the highest level on record for the region.

It marked the sixth straight day that the daily tally in the western Japan prefecture has topped the 1,000 level.

Given the sharp increase in infections, Osaka Gov. Hirofumi Yoshimura is expected to decide possibly this week whether to ask the central government for reissuance of a COVID-19 state of emergency for the prefecture.

Osaka Prefecture confirmed the same day an additional 15 patients with severe symptoms, including a man and a woman in their 40s who do not have underlying health conditions.

The prefecture has seen the resurgence in cases after the government lifted the state of emergency in Osaka and five other prefectures on March 1.

In Tokyo, the daily count averaged 586.4 over the last seven days, up 125.3 percent from the preceding week.

At present, six prefectures including Osaka and Tokyo are under a quasi-state of emergency, with local authorities requesting restaurants and bars to close by 8 p.m. in some areas.

The nationwide tally of new cases surpassed 4,000 for a fifth consecutive day the same day, with the quasi-emergency measures set to officially commence in four additional prefectures -- Aichi, Chiba, Kanagawa and Saitama -- on Tuesday.