Aid workers say eight people are confirmed dead in Vanuatu after a massive cyclone tore through the tiny South Pacific archipelago and the death toll is expected to rise much higher.

Officials from Vanuatu's National Disaster Management Office confirmed agency that eight people in and around the capital had died during the cyclone, said Chloe Morrison, a World Vision emergency communications officer in Port Vila, on Sunday.

She says officials haven't been able to assess the damage in many of the hard-hit outer islands where communications remain down.

The United Nations Office for the Co-ordination of Humanitarian Affairs says there are unconfirmed reports of at least 44 deaths in Vanuatu's northeastern islands.

Vanuatu (in red) is a sprawling country of 83 islands and 260,000 people. (Google Maps) Residents hunkered in emergency shelters for a second straight night Saturday after venturing out to find their homes damaged or blown away by the powerful storm, aid workers said.

Packing winds of 270 kilometres per hour, Cyclone Pam tore through Vanuatu early Saturday, leaving a trail of destruction.Power remained out across Vanuatu later Saturday and people on many of the outer islands had no access to running water or outside communications, said Morrison.

Morrison said communications have been so problematic that her aid group hasn't yet been able to account for many of its 76 staff on the islands.

"I can say that for anybody who wasn't in a secure shelter last night, it would have been a very, very tough time for them," she said.

Vanuatu has a population of 267,000 spread over 65 islands. About 47,000 people live in the capital.

Trees are across the roads. Some of them are piled up so you can barely see over them. - Chloe Morrison, World Vision emergency communications officer

Morrison said authorities did a good job Friday moving thousands of people in Port Vila into 23 evacuation centres. When the worst of the storm ended, many people stepped out only to find that their homes were missing a roof or had disappeared, and were forced to return to the shelters.

"It was terrifying," Morrison told CBC News. "Trees are across the roads. Some of them are piled up so you can barely see over them. There are reports that there have been casualties across all of the islands.

"This is going to need a long and sustained response. People in Vanuatu are subsistence farmers. They grow food for their own consumption. Crops will be absolutely wiped out from this."

Teetering trees and downed power lines in Port Vila have made many areas hazardous, Morrison said, adding that she had heard reports of entire villages being destroyed in more remote areas.

"It's still really quite dangerous outside. Most people are still hunkering down," she said.

54,000 children affected

The UN children's agency, UNICEF, estimated that 54,000 children were among those affected by the cyclone.

UN Secretary General Ban Ki-moon said the impact and scope of the disaster caused by the cyclone wasn't yet clear, but he feared the damage and destruction could be widespread.

"We hope the loss of life will be minimal," Ban said during the World Conference on Disaster Risk and Reduction in Japan. The UN said it was preparing to deploy emergency rapid response units.

The president of Vanuatu, Baldwin Lonsdale, who was attending the conference, told participants, "I do not really know what impact the cyclone has had on Vanuatu."

"I am speaking to you today with a heart that is so heavy," he said. "I stand to appeal on behalf of the government and the people to give a helping hand in this disaster."

Morrison said the first priority was to ensure people had adequate food, drinking water and shelter. Beyond that, she said, there would need to be a long and concerted rebuilding effort in the months ahead.

She said the winds peaked between about midnight Friday and 1 a.m. Saturday.

'Exceedingly destructive'

A westward change of course put populated areas directly in the path of Cyclone Pam. The UN Office for the Co-ordination of Humanitarian Affairs said there were unconfirmed reports of 44 deaths in Vanuatu's northeastern islands after Pam moved off its expected track.

Debris is scattered over a building in Port Vila, Vanuatu in the aftermath of Cyclone Pam. (Iss Nihemi/Associated Press)

New Zealand on Saturday pledged about $938,000 Cdn to help with relief efforts. Australia was preparing to send a crisis response team to Vanuatu if needed, Australian Foreign Minister Julie Bishop said.

"There are destructive winds, rain, flooding, landslides, sea surges and very rough seas and the storm is exceedingly destructive there," she said. "We are still assessing the situation, but we stand ready to assist."

The small island nation, located about a quarter of the way from Australia to Hawaii, has repeatedly warned it is already suffering devastating effects from climate change with the island's coastal areas being washed away, forcing resettlement to higher ground and smaller yields on traditional crops.

Scientists say it's impossible to attribute single weather events like Cyclone Pam to climate change.

The cyclone has already caused damage to other Pacific islands, including Kiribati and the Solomon Islands. Authorities in New Zealand are preparing for Cyclone Pam, which is forecast to pass north of the country on Sunday and Monday.