TOKYO • Tokyo found 107 new coronavirus cases yesterday, the most since early May, with the authorities urging residents to take extra precautions as infections continue to increase in the Japanese capital.

The figure is the highest since May 2, when Tokyo was still in the midst of its state of emergency. The city has reported more than 50 cases every day for the past week.

"We are at the stage where we must urge caution over the infection," Tokyo Governor Yuriko Koike said at a hastily scheduled press conference.

She called on residents to refrain from going to night-time entertainment establishments such as host clubs, as 44 per cent of the cases in the past week had been attributed largely to districts in Shinjuku and Ikebukuro that house thousands of such establishments.

With close contact between clients and staff and little ventilation, these clubs are ideal venues for the virus to spread.

But Ms Koike did not make any requests for businesses to close their doors, instead calling on owners to ensure that they are meeting guidelines to avoid the virus spread. She added that residents did not need to avoid businesses that were meeting these guidelines, and said there were no plans to close schools.

"We need the cooperation of residents and businesses in order to avoid a second wave," she said. "Rather than asking for Tokyo-wide restrictions, we want to send a message to the specific businesses, areas and age groups where the infection is spreading."

She unveiled a new system of monitoring criteria for the infection - designed to watch both the number of infections and the state of the medical system - on a four-point scale. The current state of infections is judged to be the third-highest on the scale.

Ms Koike is running for a second term as Tokyo governor in a vote that is set to take place on Sunday.

Despite the large number of cases, the authorities were quick to draw a distinction between the current outbreak and the situation that triggered the state of emergency in April.

Around 70 per cent of the cases yesterday were people in their 20s and 30s, who are less likely to require hospitalisation. That matches what the city has found in the past week.

It has been conducting mass testing of host clubs, with experts in the Tokyo task force attributing the rise in cases to that focused effort.

But they also cautioned that the number of infections whose path could not be confirmed was increasing, and said that if left unchecked, these could rise sixfold in four weeks, to about 160 such cases a day.

Nationwide, there are more than 18,700 cases of Covid-19 and almost 1,000 deaths.

Chief Cabinet Secretary Yoshihide Suga said that while the cases were increasing, hospitalisations were decreasing.

"We're not currently in a situation where we need to immediately declare a state of emergency again," he said.

BLOOMBERG