Strong earthquake hits off New Zealand's South Island

A strong earthquake struck off New Zealand's South Island on Tuesday, authorities said, as the country's disaster agency assessed if there were any tsunami threats.

According to some publications, the magnitude of the earthquake measured a magnitude of 6.7, while some other publications reported a magnitude of 6.8.

The United States Geological Survey said the quake, which was downgraded from an earlier magnitude of 7, happened at a depth of about 10 kilometres.

Residents of the Southland and Fiordland regions should stay away from beaches and marine areas as strong and unusual currents may present a danger, the National Emergency Management Agency said.

More than 4,700 people felt the quake, government seismic monitor Geonet said, as New Zealand media reported items falling and buildings swaying.

"We had things fall off shelf. The outdoor wooden table dancing," a user posted on Facebook, according to the New Zealand Herald newspaper.

The quake was reported at a depth of 33 km about 160km north-west of Snares Islands, the northernmost of New Zealand's sub-antarctic islands, Geonet said in an alert.

Australia's national weather bureau said there was no tsunami threat to the mainland, islands or territories.

New Zealand lies on the seismically active "Ring of Fire", a 40,000-km arc of volcanoes and ocean trenches girdling much of the Pacific Ocean.