A powerful 8.3 earthquake has struck in the South Pacific, spawning a tsunami that has swept onto the islands of Samoa and American Samoa, leaving at least 34 dead.

Officials have confirmed 14 deaths, in four different villages on the main American Samoan island of Tutuila.

Reports say people were swept out to sea by powerful waves while survivors fled for high ground.

New Zealander Graeme Ansell said the beach village of Sau Sau Beach Fale was destroyed.

"It was very quick. The whole village has been wiped out," Ansell told National Radio in Samoa. "There's not a building standing. We've all clambered up hills, and one of our party has a broken leg. There will be people in a great lot of need 'round here."

Tsunamis were spotted at Apia, Western Samoa, and at Pago Pago, American Samoa, and measured about 1.5 metres above normal sea level.

The quake happened at about 6:48 a.m. local time, and witnesses reported the ground shaking for about three minutes.

The U.S. Geological Service said the quake occurred 35 kilometres below the ocean floor, about 190 kilometres from American Samoa and 200 kilometres from Samoa.

The Pacific Tsunami Warning Center issued an alert for the South pacific region, including New Zealand, American Samoa and a number of Pacific islands.

Tsunami warnings were issued for locations as far away as Japan and Hawaii, though those warnings have since been cancelled.

American Samoa is a U.S. territory that is about halfway between Hawaii and New Zealand. About 65,000 people live there and another 175,000 live on Samoa, an independent country.

With files from The Associated Press