The pandemic-induced strain on Japan's health care system in Tokyo and other urban areas is reaching a critical phase, experts warned at a government meeting Wednesday, as the highly contagious delta variant continued to drive a rise in the country's daily infections.

The number of new COVID-19 cases nationwide totaled 15,812 on Wednesday, topping the previous record of 15,753 reported on Saturday, according to a Kyodo News tally.

Experts at a meeting of the health ministry's pandemic response panel said the situation in Tokyo, currently under its fourth state of emergency, could deteriorate despite progress in getting people vaccinated.