At least 36 people were killed when an 8.0-magnitude earthquake and devastating tsunami hit the remote Pacific islands of Samoa and American Samoa, wiping out tourist resorts and villages.

Buildings were toppled and thousands of people fled to higher ground after the offshore quake struck in the early morning, followed by giant waves which swept cars out to sea.

At least 22 were confirmed dead in American Samoa, while the Red Cross said another 14 were dead in Samoa and warned that the death toll was expected to rise amid unconfirmed reports of scores missing.

Eyewitnesses reported walls of water of between three and nine metres pounding the shore, wiping out villages and shattering holiday resorts.

One witness said the wall of water was up to 30 feet high, and a local journalist told AFP entire villages had been wiped out on Samoa's south and southwest coasts where thousands of people live.

Apia, capital of the independent state of Samoa, was evacuated as officials scrambled to get thousands of residents to higher ground.

Witnesses said cars were swept out to sea in American Samoa, where buildings were destroyed in what the US territory's Congress delegate said was a scene of "devastation".

The US Geological Survey said an 8.0-magnitude quake struck at 6:48 am (1748 GMT) at a depth of 18 kilometres, 195 kilometres south of Apia.

The Pacific Tsunami Warning Centre said waves of up to 1.57 metres had smashed into American Samoa. It issued a tsunami alert over a vast swathe of the Pacific, as far as Hawaii, which was later cancelled.

Widespread destruction

Two South Koreans were among the dead while another was missing, Seoul officials said, while Australia and New Zealand both made preparations to send emergency help.

Mike Reynolds, superintendent of the National Park of American Samoa which is headquartered in the territory's capital Pago Pago, told colleagues in California there had been widescale destruction.

National Park Service spokeswoman Holly Bundock said she had spoken to Reynolds, who was sheltering under a coconut tree.

"Park staff when they are able to make cell phone calls are calling in to our offices," she said.

"They said five tsunami waves have hit the park visitor centre in Pago Pago. It would appear park offices and the visitor centre there have been destroyed. "One of the waves was about 30 feet high."

Samoan journalist Jona Tuiletufuga told AFP there was widespread destruction with possibly thousands of people left homeless on the island.

"We are getting reports of missing people in areas were damage is extensive on the south and southeast coasts," he told AFP . "Entire villages have been wiped out."

Tuiletufuga said there were up to 70 villages in the worst-hit area and each housed from 300-800 people.

A New Zealand tourist who called Radio New Zealand to appeal for help said he was looking over an area of destruction from high ground near Apia.

"We clambered up a hill and one of the party has a broken leg. We just need help. There will be people in a great lot of need around here, it's flattened."

High waves were recorded

While information from the islands was patchy, New Zealand deputy high commissioner to Apia, David Dolphin, said most of the damage appeared to be centred on the southern coast where waves of six to eight metres were recorded.

"There are reports of some quite serious damage, at least five fatalities and quite a few reports of people missing," said Dolphin, who was on the north coast at the time.

"It was pretty scary but the house didn't appear to be falling apart so we just took what precautions we could and hunkered down," Dolphin said.

"There were windows rattling, light fittings swaying, a number of light things fell off tables and shelves," he added.

A series of powerful aftershocks rattled the South Pacific in the hours after the initial quake, which prompted Japan to issue a tsunami alert over 50 centimetre waves expected to hit the southern Ogasawara islands.

Several of the Earth's tectonic plates meet in South Pacific and violent geological activity is common. Large quakes with an under-ocean epicentre can trigger tsunamis that can have devastating effects.

In December 2004 an undersea earthquake off Indonesia's Sumatra set off a tsunami that killed more than 220,000 people around the Indian Ocean and laid waste to huge areas of coastline.

- AFP