Tokyo confirmed Sunday 313 new cases of the novel coronavirus, amid growing signs of a rebound in infections also in other areas, after a state of emergency ended throughout Japan almost a week ago.

It is the first time since Feb. 28 that the daily number reported on Sunday has topped 300 in the Japanese capital. Across Japan, nearly 1,800 new cases were reported.

Passengers look at cherry blossoms from a double-decker sightseeing bus known as "Hato Bus" on March 27, 2021, on the first weekend after the lifting of the coronavirus state of emergency. (Kyodo) ==Kyodo

Given that the number is relatively low every Sunday, a Tokyo metropolitan government official warned that "the increase may not stop from now on."

The warning came after the state of emergency, declared in early January for the Tokyo metropolitan area, was finally lifted a less than a week ago and many people were seen in commercial districts, as well as parks for the best time to view cherry blossoms, in recent days.

On Saturday, Tokyo reported 430 new cases, the biggest number since Feb. 18.

The latest figure brought the total COVID-19 cases in the capital to 119,974 and the seven-day rolling average of infections rose to 351, according to the metropolitan government. The death toll climbed to 1,725, up 20 from the previous day.

Of the 313 new infections, it said 88 involved people in their 20s, by far the biggest among all age groups.

A Kyodo News survey, based on official data through Saturday, showed that new cases increased in 28 of the country's 47 prefectures from a week earlier.

"It is unavoidable that a rebound will occur," said Satoshi Hori, a professor of infection control at Tokyo's Juntendo University.

While the Tokyo region marks a week from the end of the state of emergency on Monday, other prefectures in the country, including Miyagi, Yamagata, Osaka and Hyogo, have seen emerging signs of another resurgence in infections.

Miyagi and Yamagata, both in northeastern Japan, have declared their own state of emergency.

Yamagata logged its daily infection record on Thursday at 49, compared with less than 10 cases a day from February to mid-March.

Hori said he believes reasons behind the spread of infections differ by regions, citing such as the relaxation of measures against the virus and the emergence of new variants.

Prime Minister Yoshihide Suga declared a one-month state of emergency in the Tokyo region on Jan. 7, later expanding it to a total of 11 prefectures and extending it for most of them to March 7.

The measure was further prolonged by two weeks to March 21 for Tokyo and three neighboring prefectures -- Chiba, Kanagawa, and Saitama.