SYDNEY (REUTERS) - Fiji was assessing the damage on Sunday (Feb 21) after one of the most powerful storms recorded in the southern hemisphere tore through the Pacific island nation, flattening remote villages and killing at least five people.

Reports of damage are still flowing in from remote spots across the archipelago of about 300 islands devastated late on Saturday (Feb 20) by tropical cyclone Winston, which packed winds of 230 kmh that gusted up to 325kmh.

Several hours of harsh winds and torrential rains tore up homes and cut power, water and communications links across the nation of about 900,000 people, but the capital, Suva, escaped the brunt, after a last minute change in direction of the storm.

Prime Minister Frank Bainimarama confirmed the death toll, saying officials were working urgently to "assess and address the damage in our maritime regions".

Past cyclones had not caused so much damage, said businessman Jay Dayal, who lives near Rakiraki, on the north coast of Fiji's main island, where the cyclone hit land.

"I wouldn't be surprised if people are now starting to go without food," Dayal told Reuters. "It looks like a different country, it doesn't look like Fiji."

Police and armed forces have fanned out for rescue efforts amid concerns of flash flooding and mudslides, despite being hampered by trees and power lines blocking roads.

Fiji has declared a 30-day state of emergency, with schools ordered to shut. A nationwide curfew will continue until Monday (Feb 22) morning with electricity supply to some areas deliberately cut, to avert further damage or injury.

An elderly man died on Koro Island when a roof fell on him, authorities said earlier. In a nearby village, 50 homes were reported to have been destroyed.

"Some villages have reported that all homes have been destroyed," Jone Tuiipelehaki of the United Nations Development Program tweeted late on Saturday (Feb 20).

Alice Clements, an official with Unicef based in Suva, told Reuters she was concerned for hundreds of people who live in low-lying river areas in tin sheds, cultivating backyard crops for subsistence and sale in markets.

"The images that we're starting to see roll in are terrifying," she said by telephone, describing visuals of a car on a building roof and a small plane nose down in debris.

Australian Foreign Minister Julie Bishop said she had offered to send a P-3 Orion aircraft to carry out aerial surveillance of the outer-lying islands. "At this stage, I believe, the Fijian Government is coming to terms with the damage," Bishop told the Australian Broadcasting Corp.

About 1,200 Australians are registered as being in Fiji, although there could be many more, she added.

Australians are frequent travellers to the archipelago, thronged by around 340,000 tourists each year.

People had flocked to 758 evacuation centres on Saturday (Feb 20), while tourists hunkered down in hotel ballrooms and conference rooms in coastal areas. "We had a pretty hairy night here with the wind and the rain and we weren't even in the direct pathway of the cyclone," said Anna Cowley, a CARE Australia official based in Suva.

The United Nations Office for the Coordination of Humanitarian Affairs (OCHA) said it had an emergency response team on standby, but Bainimarama had not yet asked for help.

Airlines Virgin and Jetstar on Saturday (Feb 20) suspended flights at Fiji's international airport, and the national carrier suspended all flights.