TOKYO - A powerful typhoon hit Japan's southern Okinawa island Friday, cutting power to nearly 100,000 homes and grounding hundreds of flights.

A tree uprooted by typhoon Man-Yi in Naha city, Okinawa. A powerful typhoon hit Japan's southern Okinawa island Friday, cutting power to nearly 100,000 homes and grounding hundreds of flights. [AFP]

Man-Yi, the fourth typhoon of the season, lashed the subtropical island, whipping up waves of 12 metres (40 feet) off the Okinawa coasts and turning over trucks in roads.

Seven people have been injured in Okinawa from the typhoon since the storm approached Thursday, although none of them were in serious condition, according to police and the crisis management office.

Men trying to clear the damage clung to trees to withstand the violent wind and rain, which was so forceful it uprooted trees and knocked over large fences, television footage showed.

The storm cut off electricity supply to 99,400 households in the Okinawa archipelago.

"The winds are so strong. Our staff are on standby at branch offices, waiting for the winds to calm down," a spokeswoman at Okinawa Electric Power said.

The injured people included a 48-year-old man who fell six metres when he was fixing a television antenna on his roof, officials said.

Heavy rain was also reported in parts of the Japanese mainland, with 79 millimetres (3.16 inches) drenching the city of Hyuga on the southern island of Kyushu in one hour alone, raising fears of landslides.

Man-yi, described as "extremely strong" by the meteorological agency, is packing wind gusts of up to 252 kilometres an hour (156 miles an hour).

The storm remained over the island 50 kilometres (30 miles) north of the Okinawan capital of Naha at midday and was moving north at 20 kilometres (12 miles) an hour.

The typhoon may cross the Tokyo region early Sunday after lashing western Japan, the meteorological agency said, warning of torrential rain, flooding and landslides.

Airline companies have cancelled more than 300 flights, according to public broadcaster NHK.

Man-Yi is named after a strait that is now a reservoir in Hong Kong.

Japan and other nations in the western Pacific are hit each year by lethal typhoons. Last year, Typhoon Shanshan killed nine people in Japan and injured 300 others.