The quake at 6:16pm (0516 GMT) was centred 204 kilometres (126 miles) deep and about 300 kilometres northeast of Auckland.

The tremor was not widely felt on the mainland and police said there were no immediate reports of damage or injury.

A shallow 6.3-magnitude quake devastated New Zealand's second largest city of Christchurch in February last year, leaving 185 people dead.

The sparsely populated country sits on the so-called "Ring of Fire", the boundary of the Australian and Pacific tectonic plates, and experiences up to 15,000 tremors a year.