A cyclone which tore through Vanuatu badly damaged or destroyed up to 90% of houses in the Pacific island state's capital Port Vila, Oxfam says.

A Red Cross spokesman described the situation as apocalyptic - in some areas, entire villages were swept away.

At least eight people are reported to have been killed but it is feared the toll will rise sharply as rescuers reach outlying islands.

Thousands of people spent a second night in shelters.

OxfamInVanuatu: the morning after #CyclonePam in Port Vila Vanuatu pic.twitter.com/qT9jOCT5fp

— colin (@Colincvr) March 14, 2015

Oxfam Australia said entire communities had been "blown away".

"People of #Vanuatu are going to need a lot of help to rebuild their homes and their lives", #CyclonePam http://t.co/g5UMHtL211

— Oxfam International (@Oxfam) March 14, 2015

#CyclonePam is "catastrophic & not only to buildings... we expect that people's livelihoods will be disrupted for months ahead" @HelenSzoke

— Oxfam Australia (@OxfamAustralia) March 14, 2015

“We have no power or running water and are still not able to move around freely," - Oxfam's @Colincvr in #Vanuatu #CyclonePam

— Oxfam International (@Oxfam) March 14, 2015

The category-five storm, with winds of up to 270km/h, veered off its expected course and struck populated areas on Friday night.

Vanuatu's population of 267,000 is spread over 65 islands with about 47,000 people living in Port Vila.

In a statement today, Oxfam Australia said up to 90 percent of housing in Port Vila had reportedly been seriously damaged.

"This is likely to be one of the worst disasters ever seen in the Pacific," said Oxfam's Colin Collet van Rooyen in Port Vila.

"The scale of humanitarian need will be enormous and the proud people of Vanuatu are going to need a lot of help to rebuild their homes and their lives."

Immediate priorities, he said, were providing shelter, clean water and sanitation.

Port Vila's airport has been closed since the cyclone struck but officials said they hoped it might partly reopen today to allow in the first relief planes.

A UN disaster assessment team is due to arrive in Vanuatu in the coming hours.

'One toilet between 300'

Mark Le Roux, of the Adventist Development and Relief Agency, told the BBC the situation in Port Vila was "pretty grim".

"We have 20 evacuation centres with about 2,000 people in them, some of our evacuation centres have up to 300 people sharing one toilet," he said.

Chloe Morrison, an emergency communications officer with World Vision in Port Vila, said residents had woken to much calmer weather today.

She said communications were still down in many areas and her group had been unable to account for many of its 76 staff members on the islands.

She said it would have been a "very, very tough time" for anyone not in a secure shelter during the cyclone.

Earlier, Vanuatu's President Baldwin Lonsdale made an impassioned plea for international help.

"I am speaking to you today with a heart that is so heavy," he said at the UN's World Conference on Disaster Risk and Reduction in Japan.

"I stand to appeal on behalf of the government and the people to give a helping hand in this disaster."

The extent of the devastation is unlikely to be known for several days, said Tom Skirrow, Save the Children's Vanuatu country director.

Unconfirmed reports yesterday said 44 people had died in Penama province in the north-east of Vanuatu, according to the UN's Office for the Co-ordination for Humanitarian Assistance.

Australia says it is preparing to send a crisis response team to Vanuatu if needed. New Zealand pledged $741,000, the EU promised €1m and the UK said it would give up to £2m in aid.

Pam had already caused major damage on other Pacific islands, including Kiribati and the Solomon Islands.

Tuvalu, a group of nine tiny islands north-east of Vanuatu, also declared a state of emergency after the cyclone caused flash floods there.