Japan placed Tokyo under a new, month-long state of "quasi-emergency" on Friday to combat surging COVID-19 infections, less than a month after the capital and host of the Summer Olympics lifted a broader state of emergency.

Prime Minister Yoshihide Suga said the restrictions were needed to prevent regional outbreaks from turning into a nationwide wave.

"We ask that people to refrain from unnecessary travel between prefectures as much as possible," Suga said in televised remarks.