The Tokyo metropolitan government raised its COVID-19 alert to the second-highest of four levels Thursday amid a continuous rise in coronavirus infections for two consecutive weeks.

Experts attending a monitoring meeting of the metropolitan government made the decision and warned that the virus is spreading again, stressing the importance of promoting vaccination among young people.

On Thursday, Tokyo reported 3,621 new daily cases, up about 1,200 from the same day last week. The nationwide tally, meanwhile, stood at 23,448 cases, up about 6,700 from the week earlier.

The seven-day rolling average of new infections in Tokyo as of Wednesday was up 38 percent from the previous week, marking an increase of two consecutive weeks following a 10 percent increase last week.

The highly contagious BA.5 strain of Omicron variant is replacing the BA.2 subvariant in the capital as suspected cases of BA.5 account for about 25 percent of new infections.

A coronavirus panel of the health ministry on Thursday also alerted to the BA.5 strain's increasing dominance across the country and a possible further rise in COVID-19 cases.

Nationwide cases of the BA.5 strain are projected to account for 24 percent of the total in the first week of July and rise over 50 percent in the following week, according to the National Institute of Infectious Diseases.

Norio Omagari, head of the Disease Control and Prevention Center at the National Center for Global Health and Medicine, said that the daily figure in Tokyo might increase to over 5,000 by mid-July.

"An increase in COVID-19 cases during the sixth wave (from January to March) had a great impact on social activities. We need to make sure that it does not get repeated," Omagari said at the metropolitan government's meeting.

Masataka Inokuchi, a vice chairman of the Tokyo Medical Association, pointed that the rapid increase in heatstroke patients due to high temperature in the capital has placed a heavy burden on emergency medical services, warning that the situation needs to be monitored for its possible impact on the acceptance of COVID-19 patients.

Tokyo's temperature on Thursday climbed to 36.4 C, the highest for June since comparable data became available in 1875, according to the weather agency.