A powerful 7.0-magnitude earthquake struck off New Caledonia's Loyalty Islands in the South Pacific, the US Geological Survey said Friday, but there was no tsunami warning in effect.

There were no immediate reports of damage from the quake, which hit at 3.16 am (1616 GMT Thursday).

In a revised statement the USGS said the quake hit at a shallow depth of 4.6 kilometres (2.9 miles), 125 kilometers (80 miles) northeast of Tadine in the Loyalty Islands, New Caledonia, and 135 kilometres southwest of Vanuatu.

The USGS lowered the magnitude from 7.3 after seismologists reviewed the event.

A series of aftershocks, the most powerful measuring 5.9-magnitude, rumbled through the area after the quake.

The Hawaii-based Pacific Tsunami Warning Center said there was no warnings or advisories in effect following the quake.

The area has been hit by a series of powerful earthquakes and aftershocks since December 26 last year when a 7.3-magnitude quake which struck near Vanuatu.

The Loyalty Islands, part of the French territory of New Calendonia, are in the "Pacific Ring af Fire" known for its seismic and volcanic activity caused by friction between moving plates in the Earth's crust.