Emergency aid and relief supplies have begun to arrive in Vanuatu after Tropical Cyclone Pam tore through the Pacific nation, killing at least eight people in what has been described as the region's worst natural disaster in "living memory".

Charity groups said they were doing all they could to get food and supplies into the island nation, and commercial flights were scheduled to resume today.

Save the Children director Tim Nelson said up to 150,000 people had been affected by the cyclone, with 42,000 homes damaged.

"It was incomprehensible what was bearing down," he said.

"No-one here in living memory has seen anything like this."

Mr Nelson estimated at least 15,000 homes were now uninhabitable and said he expected the death toll to rise significantly.

"I imagine the number of casualties and fatalities unfortunately are likely to rise," he said.

"We know of thousands in evacuation centres.

"The water is contaminated and we are not sure people have got the message they can't drink the water."

Mr Nelson said the last major cyclone hit Vanuatu in 1987 and it was nothing like Pam.

"A hospital has lost its roofing, there is a shortage of beds and most worrying, the medical repository where they house their drugs has lost [its] roof."

"These people are resilient, they do most things themselves."

He said full recovery from the event would take years, with thousands of homes to be rebuilt.

"To get people's lives on track, we hope within a couple of months we can have schools working again, we can have hospitals open.

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"That is the main focus, restoring normality to the lives of people and children."

The Red Cross in Vanuatu said nearly all the houses in Port Vila had been destroyed, and many locals were staying in the evacuation centre.

"We have people everywhere, they're going in to the evacuation centre," CEO Jacqueline de Gaillarde said.

"We count about 2,000 people but they stay only during the night because in the morning they rush to their place to make sure their belongings are safe.

"Right now, there is no more rice in town and all those who have gardens have nothing left. And in days to come we are going to face a major issue about food."

Richard Tatwin of the Presbyterian Church of Vanuatu said the poorest people were worst affected.

"Shelter is the biggest need at the moment, plus, depending on the situation of each family if it's a low income earner, food too as well," he said.

"And clothing, if all the clothes have been blown away by the wind, by the cyclone."

Prime Minister Tony Abbott indicated RAAF flights would deliver extra personnel and supplies today, with two additional military planes set to fly over as part of the international effort.

Foreign Minister Julie Bishop said Australians wanting to come home from Vanuatu would be offered seats on military aircraft returning from the disaster zone.

"We are giving priority to the elderly, the sick, pregnant women, children and the like," Ms Bishop told the ABC's AM program.

Mr Abbott told parliament around 1,500 Australians are known to be in Vanuatu, but consular efforts are continuing to contact others.

"If people cannot contact their families and friends directly, they should contact the Department of Foreign Affairs consular emergency centre which will do what it can to assist," he said.

Ms Bishop said no Australian casualties had been reported in Vanuatu following Friday's deadly cyclone.

"Reconnaissance over the southern islands will obviously inform our understanding of whether there are any more areas we need to check for Australians that may be there," Ms Bishop said.

"The people of Vanuatu are obviously uppermost in our thoughts as well."

Widespread flooding as sea surges reached eight metres

Aid officials earlier said the storm was comparable in strength to Typhoon Haiyan, which hit the Philippines in 2013 and killed more than 6,000 people, and looked set to be one of the worst natural disasters the Pacific region had ever experienced.

Witnesses in Port Vila described sea surges of up to eight metres and widespread flooding as the cyclone hit on the weekend.

Sorry, this video has expired Aid worker describes Vanuatu destruction

Dr Len Notaras, who heads the Darwin-based National Critical Care and Trauma Response Centre, said a team of 10 people from Australia had recently arrived in Vanuatu.

He said initial reports from the team were of "total devastation".

"This is not dissimilar to the response to Pakistan back in 2010, where we saw just on 60,000 patients in 70 days," Dr Notaras said.

"This is a third or fourth world country, absolute devastation, with destruction of their hospital and so on."

Photos taken by CARE Australia while flying aid into Port Vila showed the scale of the devastation caused to communities, with many homes destroyed.

Alice Clements, a spokeswoman for the UN Children's Fund (UNICEF) in Port Vila, said it was as if a bomb had gone off in the centre of town.

Australia's contribution was part of an initial assistance package announced by Foreign Affair's Minister Julie Bishop, which included $5 million for Australian NGOs and UN agencies on the ground in Vanuatu.

An RAAF plane will be flying to the outer islands of Vanuatu on Monday to assess the damage caused by the storm.

Mr Abbott said he had rung his counterparts in the United Kingdom and Vanuatu to discuss relief efforts.

He said Vanuatu prime minister Joe Natuman thanked Australia and its people for their assistance.

New Zealand had offered $NZ2.5 million in initial aid, while Britain, which jointly ruled Vanuatu with France until independence in 1980, had offered up to two million pounds ($3.86 million) in assistance.

The World Bank said it was exploring a swift insurance payout to the government.

Vanuatu's president 'fears the worst' in outer islands

Vanuatu's president Baldwin Lonsdale had been in Japan when the cyclone hit, attending a UN disaster recovery conference.

Mr Lonsdale said he feared the storm's impact would be "the very, very, very worst" in isolated outer islands.

Appearing visibly upset at a media conference, he said damage was still being assessed but most houses in Port Vila had been either damaged or destroyed.

"People are finding shelter where they can live for the night," he said.

Mr Lonsdale said he had been unable to communicate with his own family.

"My heart is for the people, and everyone has that same feeling.

"Because we don't know what happened to our family, there's a breakdown in communication so we cannot reach our families, and we do not know whether our families are safe or not.

"As a leader of the nation, my whole heart is for the whole people of the nation."

Vanuatu's lands minister Ralph Regenvanu said the cyclone was so strong that he felt his cement house shaking.

"We have a very solid cement house and the whole house was shaking and it was like the windows were being sucked out of the house," he said.

"There's going to be a big problem with water and water-borne diseases. That's definitely something that we're very concerned about."

ABC/Reuters