An undersea earthquake off the South Pacific island of Tonga sparked fears of a tsunami.

The US Pacific Tsunami Warning Center issued a tsunami warning after the magnitude 7.9 quake struck 132 miles southeast of the island.

But the warning was later cancelled amid no reports of damage or of sea levels rising in Tonga or nearby Fiji.

An undersea volcanic eruption off Tonga earlier this week, thought to have been caused by a strong sharp tremor, sent plumes of white and grey smoke shooting into the sky.

Spectacular columns were sent spewing out of the sea about six miles from the southwest coast of the main island of Tongatapu, an area where up to 36 undersea volcanoes are clustered.

The eruptions do not pose any danger to those living on nearby islands, and there have been no reports of fish or other animals being affected.

Tonga, a 170-island archipelago about halfway between Australia and Tahiti, is part of the Pacific "ring of fire" - an arc of earthquake and volcanic zones stretching from Chile in South America through Alaska and down through Vanuatu to Tonga.

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