Sea level readings following the quake, which had a magnitude of up to 7.0, indicated a tsunami was generated, the Pacific Tsunami Warning Centre said.

But it said a "destructive Pacific-wide tsunami" was not expected.

The quake struck some 300km (185 miles) south-west of Samoa. Waves of 8cm (3.1 inches) high were reported in the American Samoan town of Pago Pago.

One policeman in the capital Apia said buildings swayed and shook for about five minutes, but there was no damage or casualties.

"It was not so strong," he told the Associated Press.

The Hawaii-based warning centre said the tsunami "may have been destructive along coasts near the earthquake epicentre".

No damage was immediately reported.

Samoa is a small chain of islands that lies half way between New Zealand and Hawaii.

Countries around the Indian and Pacific Oceans have been testing systems to warn of approaching tsunamis since the 26 December 2004 earthquake unleashed a tsunami that killed more than 200,000 people.

The 9.3 magnitude quake, off the coast of Indonesia, sent waves thousands of kilometres across the Indian Ocean, hitting countries as far apart as the Maldives, Sri Lanka and Somalia.