People wait in Te Aro Park after being evacuated from nearby buildings following an earthquake on November 14, 2016 in Wellington, New Zealand. [Photo/VCG]

Other areas affected by the earthquakes and landslideshad adequate communication and supplies.

"The economic impact on earthquake-affected areas will also be assessed in the coming days," said Brownlee.

"Agencies will continue monitoring the situation closely. The public should be advised that aftershocks will continue to occur."

The Ministry of Civil Defence and Emergency Management (MCDEM) said local state of emergency had been declared in Kaikoura and the neighboring Hurunui district.

"Civil Defence and Emergency Management groups across the country are sending people to the region to help," MCDEM management director Sarah Stuart-Black said in a statement.

Key and Brownlee said in a televised press conference earlier Monday that it was impossible to rule out further fatalities.

"On the very best information we have at the moment, we think it's only likely to be two, but of course there are isolated parts of the country in which we don't have perfect eyes on so we can't be 100 percent sure, but we're not aware of any that we're not reporting," said Key.

Structural engineers were also checking buildings in the capital, Wellington, where the quake was felt strongly.

The quake was centered 15 km northeast of Culverden, on the east of the South Island, and struck at 12:02 am on Monday, according to the government's GeoNet monitoring service.

It is being followed by many aftershocks, the largest of them a magnitude of 6.3.