Helicopters, boats and thousands of troops have been deployed across Japan to rescue people stranded in flooded homes as the death toll from Typhoon Hagibis climbed to at least 23 with more than a dozen missing.

Government spokesman Yoshihide Suga said 27,000 military troops and other rescue crews were taking part in the operation. Some 376,000 homes were without electricity, and 14,000 homes lacked running water, he said.

Public broadcaster NHK said 14 rivers across the nation had flooded, some spilling out in more than one spot.

Authorities warned of a risk of mudslides. Among the reported deaths were those whose homes were buried in landslides. Other fatalities included people who were swept away by raging rivers.

Evacuation centres had been set up in coastal towns with tens of thousands of people seeking shelter. Kyodo News service said evacuation warnings had been issued to more than six million people.

The typhoon disrupted a three-day weekend in Japan that includes Sports Day on Monday. Qualifying for a Formula One race in Suzuka was pushed from Saturday to Sunday.