Magnitude 6.6 earthquake strikes near Tonga

A tsunami warning for Tonga has been cancelled following a 6.6-magnitude earthquake near Fangale'ounga on Monday.

Tonga's Metservice had issued the warning just before 10am local time (9am NZ time).

At 11am, it said that based on tide gauge readings and advice from the Pacific Tsunami Warning Centre, the main threat had passed.

Small unusual waves, currents, and abnormal tides may still affect some beaches and harbours for hours.

The US Geological Survey said the kingdom was shaken by a 6.6 quake, 70km northwest of Fangale'ounga.

The USGS said the quake was 112km deep.

The 6.3 magnitude earthquake struck NNW of Port Vila. Photo: Supplied/United States Geological Survey (USGS)

On Sunday, a strong earthquake struck the South Pacific Island nation of Vanuatu, but there were no tsunami warnings or immediate reports of damage.

The quake had a preliminary magnitude of 6.3 when it hit at 9.23am local time (10.23am NZT), the US Geological Survey said.

Its epicenter was 83km northwest of the capital, Port Vila, at a depth of 29km.

The Hawaii-based Pacific Tsunami Warning Center said there was no risk of the quake causing a tsunami.