TOKYO • The daily number of new coronavirus cases in Tokyo climbed to 55 yesterday, Governor Yuriko Koike said, the highest tally in 1½ months, after a cluster of infections was found at an unnamed office in the Japanese capital.

"Fifty-five daily cases was a bit of a shock to me when I first heard it," Ms Koike told reporters.

"But our current situation is different from back in March and April, namely because our medical system is significantly different."

The metropolis, with a population of 14 million, has sought to keep new cases below 20 a day since Japan lifted a state of emergency on May 25.

Of the 55 new cases, nine were confirmed at the workplace, which already had seven recorded infections, Ms Koike said. The new cases might have emerged outside the office where the employees had a meeting, she added.

Speaking before the latest figure was reported, Ms Koike had warned of a "large number" yesterday as more positive test results followed a cluster of seven infections previously found at the office.

"Clusters in the workplace have become a big problem lately" as people have emerged from the capital's "Stay Home" initiative, the governor had told reporters earlier.

"Businesses like eateries are taking steps to create partitions and such, but it's difficult to see what kind of precautions are being taken at offices," Ms Koike said.

"The latest case tells us that offices can become clusters too, so we'd like everyone to think again about what a new normal for the workplace should look like."

Until now, Ms Koike had repeatedly commented on night-time establishments as being the major source of risk.

She said that in addition to the latest results from the office, more than 10 cases emerged yesterday from group testing in Shinjuku - an area known for its nightlife.

Ms Koike's comments highlight the city's concern over the possibility of a second wave of infections, a risk many regions are now facing after initially containing the disease.

Daily cases in Tokyo have moved in a range of around 20 to 40 for much of the past week.

A seven-day average of 50 cases a day was one of the conditions that could lead to a reimposition of curbs on businesses in a series of criteria Ms Koike laid out last month. That figure now stands at 38.

Traffic at major stations in the capital has been slowly returning to normal since the state of emergency was lifted late last month as workers began to return to the office.

All restrictions on businesses in the capital were lifted last Friday as planned, however, and the government has been encouraging residents to resume travel to other regions.

Despite its recent spike in cases, Tokyo - like the rest of Japan - has been spared the kind of explosive outbreak seen elsewhere, with some 5,800 coronavirus cases and 323 deaths so far.

In all of Japan, about 18,000 have tested positive and more than 950 have died so far.

REUTERS, BLOOMBERG