Japan reported over 970 new cases of the oronavirus on Wednesday, as urban centers including Tokyo and Osaka continued to see high levels of infection.

Tokyo confirmed 222 new coronavirus cases, of which around 67 percent had unknown transmission routes. The metropolitan government said those in their 20s and 30s accounted for 60 percent of the infections, while 26 individuals were in their 60s or above.

The single-day increase in the capital compared with 188 on Tuesday, 197 on Monday and 331 on Sunday.

Tokyo's cumulative total now stands at over 16,474, while that of the whole country topped 52,000.

Average daily new infections in Tokyo over the last seven days stood at 312.7, according to the metropolitan government, which has raised its own alert for the pandemic to the highest of four levels, meaning "infections are spreading."

Tokyo has requested residents to refrain from traveling, including to hometowns during the Bon holiday season, and for karaoke venues and establishments serving alcohol to close by 10 p.m. until the end of August.