SYDNEY, March 14 (Reuters) - Winds of up to 340 kilometers an hour (210 mph) ripped metal roofs off houses and downed trees in the Pacific island nation of Vanuatu on Saturday, as relief agencies braced for a major rescue operation and unconfirmed reports said dozens had died.
Witnesses described sea surges of up to eight meters (yards) and flooding throughout the capital Port Vila after Category 5 Cyclone Pam hit the country. Communications with the outside world were largely knocked out.
Aid officials said the storm may be unprecedented in the island's history and could be one of the worst natural disasters the Pacific region has ever seen, hitting Papua New Guinea and the Solomon Islands before reaching Vanuatu late on Friday.
Satellite photos showed the storm covering virtually the entire archipelago. Outlying islands may take weeks to reach, aid officials said, while a lack of clean water and widespread crop damage meant there was a real risk of hunger and disease.
"It felt like the world was going to end," Alice Clements, a spokeswoman for the UN Children's Fund (UNICEF), told Reuters by cellphone from Port Vila. "It's like a bomb has gone off in the center of the town. There is no power. There is no water.
"We are hearing unconfirmed reports of casualties and lots of wounded. People are asking for help. Even in Port Vila there are still gale-force winds. There are unconfirmed reports of fatalities in Port Vila."
Clements said residents had the roofs ripped off their homes as they tried to shelter and then found themselves unable to move because of the strong winds. Many of Vanuatu's 260,000 people live in buildings made of thatch.
The Vanuatu National Disaster Management Office had red alerts in place for several provinces, but late on Saturday the storm was beginning to move off slowly to the south.
U.N. relief workers were preparing to send in teams on Sunday, but with the airport closed and winds still high it remained unclear whether they would be able to land.
This video, uploaded to YouTube by Isso Nihmei, shows the damage of Cyclone Pam in Venuatu.
Unconfirmed reports said that 44 people died in outlying northeastern islands, the U.N. Office for the Coordination of Humanitarian Affairs (UNOCHA) said. Figures from the government were not available and aid workers.
Aid officials said at least one person died in Papua New Guinea's outlying islands, but many areas were cut off.
U.N. officials said it would be days at least before the true picture was known.
"We fear the worst," Sune Gudnitz, UNOCHA's regional head told Reuters from Fiji. "Vanuatu is a very vulnerable place because of its location in the middle of the ocean.
"It is possible that there will be a death toll that could be high. I think it is a well grounded fear."
Officials with World Vision said a meeting was under way on Saturday to prepare a coordinated response. Spokeswoman Chloe Morrison described the storm as "terrifying" and said many of the country's 83 islands would be difficult to reach.
"Trees are across the roads. Some of them are piled up so you can barely see over them," she said.
A man stands in flood waters March 13, 2015 on the island of Kiribati. Cyclone Pam is pounding South Pacific islands with hurricane force winds, huge ocean swells and flash flooding. (Photo by Plan International Australia via Getty Images)
Morrison said there were reports of casualties across all of the islands, adding that people were describing it as the worst disaster they had ever experienced.
"This is going to need a long and sustained response. Crops will be absolutely wiped out from this," Morrison said.
Vanuatu's economy is highly dependent on tourism, which will also be badly hit in the coming months, she said.
Cyclone Pam is the most severe storm to hit the tiny Pacific island nation since at least 1987. Aid officials said it was comparable in strength to Typhoon Haiyan, which hit the Philippines in 2013 and killed more than 6,000 people.
Australian Foreign Minister Julie Bishop said Canberra would be willing to offer whatever help it could.
Formerly known as the New Hebrides, Vanuatu was jointly ruled by France and Britain until independence in 1980. It is among the world's poorest countries and is highly prone to natural disasters, including earthquakes, tsunamis and storms. (Editing by Kim Coghill)