An undersea volcanic eruption was observed off the South Pacific island of Tonga on Saturday.

Tsunami waves were recorded soon after in areas of the Pacific.

The Japan Meteorological Agency says the eruption occurred at the Hunga Tonga-Hunga Ha'apai underwater volcano, shortly after 04:00 UTC.

Images from the Himawari weather observation satellite show smoke from the volcano spread in a concentric manner and had covered an area of about 200 kilometers in diameter about one hour later.

Officials at the Wellington Volcanic Ash Advisory Center in New Zealand say the cloud of ash reached a height of about 15,000 meters.

The Pacific Tsunami Warning Center says tsunami waves measuring about 80 centimeters were observed in the capital of Tonga... and about 60 centimeters in the capital of American Samoa.

Tsunami warnings were issued across wide areas of the South Pacific. Australia has also urged local residents in the south eastern coastal area to be cautious.

The US Tsunami Warning System initially said a magnitude 7.6 earthquake had been recorded in Tonga at 06:40 UTC on Saturday, but it was later downgraded.