Tokyo reported 664 daily cases of the novel coronavirus on Friday, with its cumulative total topping 50,000, as concern about the strain on Japan's medical system continued to grow.

The figures came a day after the capital reported a record 822 daily infections, marking an all-time high for the second day in a row. Its cumulative total now stands at 50,154, with 561 dead.

More than 2,800 cases were reported by local authorities across the country on Friday, bringing the cumulative total to over 194,000. The death toll now stands at about 2,900.

The Tokyo metropolitan government on Thursday raised its alert regarding the strain on the medical system to the highest of four levels. It is the first time the most severe level has been reached since the outbreak of the virus.

"The virus' transmission routes and breakdown by age of patients have not changed recently. But the pace of increase in the number of infected people has accelerated," said a metropolitan government official.

It took around three weeks for the number of cases in Tokyo to reach 50,000 after hitting 40,000 on Nov. 28, while it took about a month to rise from 30,000 to 40,000, according to the metropolitan government.

Of the 664 new cases, 185 people were in their 20s, followed by 139 in their 30s and 101 in their 40s. There were 83 infected people aged 65 or older.

Tokyo Gov. Yuriko Koike has urged people to take increased anti-virus measures during the year-end and New Year holiday period.

The number of COVID-19 patients has been high since mid-November in Tokyo, the hardest hit of the country's 47 prefectures.