WELLINGTON (AFP) - A powerful 6.7 magnitude earthquake shook the east coast of New Zealand on Monday, but authorities ruled out an immediate tsunami threat.

The quake, which struck at 10.33 am (2233 GMT Sunday) was centred at sea nearly 200 kilometres from the eastern North Island city of Gisborne and 35 kilometres deep, the US Geological Survey said.

New Zealand's civil defence organisation said it was "unlikely to have caused a tsunami that will pose a threat to New Zealand."