An earthquake of magnitude 7.6 struck off Tonga, the United States Geological Survey said.

The quake struck at 4am NZT, with its epicentre at a distance of 95km west-north-west of Hihifo, Tonga, the USGS said.

It was at a depth of 210km.

The US Tsunami Warning System said there was no tsunami warning after the earthquake.

The quake was followed by a 5.1 magnitude aftershock at 4.30am NZT.

Hihifo is the main village on the island of Niuatoputapu north of the Tonga main island group.

The quake was felt in American Samoa. A journalist in Tuālāuta County said the shaking lasted at least a minute or two.