The Pacific Tsunami Warning Center issued a local tsunami warning but said there was no threat of a widespread destructive tsunami.
The quake struck at 1:03 am (1303 Monday GMT) around 550 kilometres (350 miles) east of Auckland, USGS said, with an epicentre 90 kilometres (55 miles) below the surface.
USGS had earlier measured the magnitude at 6.4.
The epicentre lay southwest of the Kermadec Islands, which lie around 1,000 kilometres northeast of New Zealand.
New Zealand sits on the so-called Pacific "ring of fire", a zone of frequent tectonic activity, and is often hit by earthquakes.
The country`s second largest city Christchurch was devastated by a 6.3-magnitude quake in February, which claimed 181 lives and followed a more powerful but less destructive 7.1 quake last September. (*)
Editor: Kunto Wibisono
Copyright © ANTARA 2011
