Japan "has no doubt entered" a seventh wave of coronavirus infections though there is currently no need for new movement restrictions, the head of a government COVID-19 experts panel told reporters on Monday.

Shigeru Omi said the latest increase reflects the arrival of "a new wave" and is likely fueled by the spread of the BA.5 subvariant of the Omicron variant, which is said to be highly transmissible.

Japan's top coronavirus adviser Shigeru Omi gives an interview in Tokyo on April 15, 2022. (Kyodo) ==Kyodo

"I said that if everyone does what they can do, there is no need at this point to impose movement restrictions," Omi said after meeting with Prime Minister Fumio Kishida at the premier's office.

Cases are rising nationally with a total of 37,143 new cases reported Monday, a 120 percent increase from the same day last week. Tokyo and Osaka Prefecture also saw more than twice as many cases at 6,231 and 2,515, respectively.

The Osaka prefectural government raised its alert level by one notch from "green" to "yellow" on the same day and asked nursing homes in the populous prefecture to refrain from allowing visitors for the time being, starting Tuesday.

"The important thing is how we can prevent cluster cases" at nursing homes, Gov. Hirofumi Yoshimura told a meeting of the local government's COVID-19 task force.

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