Japan's capital Tokyo confirmed 534 new coronavirus cases Thursday to hit another record and Prime Minister Yoshihide Suga said the country was on "maximum alert."
Tokyo saw daily cases top 500 for the first time and hit a record for the second consecutive day, according to officials.
The new COVID-19 infections have prompted the national and local governments to consider new curbs on movement and businesses.
"The infection situation in Tokyo has entered a phase of rapid expansion," one expert said.
Japan's third wave saw a national daily record of 2,203 new cases Wednesday. Tokyo accounted for 493 of these cases.
Suga instructed the country's coronavirus response officials and health ministry to take additional measures to prevent the spread of the virus based on discussions at a two-day expert panel meeting which will continue until Friday.
Given the recent resurgence in infections, the Tokyo Metropolitan Government raised its virus alert to the highest of four levels Thursday, officials said.
The Ministry of Health, Labor and Welfare said the rise in new cases might confirm the existence of a third wave of infections.
Tokyo's neighboring prefectures of Kanagawa and Saitama also reported record daily high numbers. Osaka saw more than 200 new infections for a second straight day. The third wave boosted hospitalizations.
The health ministry said the number of serious cases rose to 276 Tuesday - a 70% jump over the past two weeks.
Warning of an "impending crisis," the Japan Medical Association has urged people to stay at home for the upcoming three-day weekend. "Thorough measures to control the virus are the best way to help the economy," the association said in a statement.
Association president Dr. Toshio Nakagawa asked the public to refrain from unnecessary travel, especially to and from regions where cases are surging. "Please do not get complacent about the coronavirus," he said. "We can prevent it from spreading across the country through the combination of each of our actions."
Dr. Shigeru Omi said if COVID-19 keeps spreading at this rapid pace, "it will be difficult to bring it under control through the public's efforts alone, and stronger measures might become necessary."
