SYDNEY (REUTERS) - A powerful earthquake measuring 6.4 magnitude struck 572km beneath the earth's surface on Friday (May 27), about 340km west of the South Pacific island nation of Tonga, the United States Geological Survey (USGS) reported.

There was no indication of a tsunami warning, according to the Pacific Tsunami Warning Centre.

The temblor was revised down from an initial reading of 6.5.