The Ministry of Civil Defence says there is a possible tsunami risk to New Zealand.

An earthquake initially measured at 6.6 struck the Fiordland area at 22 minutes past nine tonight. It was followed 19 minutes later by a 6.1 magnitude aftershock.

Japan's meteorological agency says the magnitude of the original tremor was 7.8, and Civil Defence has received information from the Pacific Tsunami Warning Centre in Hawaii. Civil Defence has issued a statement saying the message is NOT a warning but is rather an advisory for the public to listen for further information.

Southland Civil Defence has activated its Emergency Operations Centre to assess damage reports following tonight's earthquake.

Sky News says a tsunami warning has been issued for Australia's south-east coast.