Typhoon Man-yi, described as one of the strongest in memory, whipped up waves of 12 metres (40 feet) off the subtropical island's coasts and overturned trucks.

The typhoon is expected to smash into mainland Japan's southern island of Kyushu on Saturday and may then hit the Tokyo region, according to the Japan Meteorological Agency.

In Okinawa, television footage showed men who had been trying to clear the damage forced to cling to trees to withstand the violent wind and rain, which uprooted trees and flattened large fences.

"This is one of the biggest typhoons we've experienced in Okinawa," a local hotel employee said by telephone.

"We islanders are very nervous. It's fairly dangerous to go out or even drive a car as trash and broken trees are flying in the air," he said.

Two men aged 78 and 66 were seriously hurt when they were blown over in high winds, news agency Kyodo reported, citing the local authorities.

They were among 31 people injured in Okinawa alone since the typhoon approached Thursday, it said, adding that the storm had cut off electricity to 134,000 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.

In a separate incident, a 48-year-old man was injured after falling six metres while trying to fix a television antenna on his roof, officials said.

More than 10,000 people were forced to evacuate their homes as the typhoon approached.

Authorities in Kagoshima prefecture on the southern island of Kyushu advised more than 8,760 people to evacuate, while in neighbouring Miyazaki prefecture, 2,390 people were told to evacuate as 78 houses were flooded.

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