More than 1,000 people have been forced to flee their homes as wildfires threaten homes in New Zealand's third-largest city.

The fire in the Port Hills district of Christchurch began earlier this week and was thought to have been started by an electrical problem.

It spread rapidly overnight on Wednesday to cover around 2,000 hectares and is spreading.

A state of emergency has been declared and Prime Minister Bill English has arrived in the city to monitor the situation.

The Fire Service has 40 crews with 45 pumps and tankers and there are 26 rural fire crews with more than 200 personnel fighting to contain the blaze. Australian Prime Minister Malcolm Turnbull has also offered to send help.


More than a dozen helicopters have been brought in from across the country, along with three fixed-wing aircraft.

Image: New Zealand Prime Minister Bill English learns the latest on the fires in Christchurch's Port Hills. Pic: Christchurch City Council Newsline

Christchurch City Council said just before midday on Thursday local time that 11 homes and two sheds had been lost to the flames, although the situation was "constantly changing".

Emergency management spokesman Richard McNamara told Radio New Zealand: "Yesterday we were chasing a monster - we were trying to catch it, and you add in wind and it becomes totally uncontrollable."

James Frost, 34, told the New Zealand Herald that the home he shares with partner burnt down just hours after he insured it.

Mr Frost had previously lost a home to Christchurch's 2011 earthquake before living in Australia for a few years.

"From what we could see, our house was actually glowing," Mr Frost said.

"It was just by chance we spoke to a gentleman whose partner was in the police and she was able to say, 'yeah that house is gone'.

Image: There are hopes a weather change later this week will help firefighters. Pic: Christchurch City Council Newsline

"We just sat and watched the hills burn for a while, for a bit of closure."

Mr Frost said he still feels "numb" but "so lucky" that he got insured.

It is hoped that a change in wind direction later this week will lower temperatures and humidity, slowing the progress of the fire.

On Tuesday, Steve Askin, a former New Zealand soldier and helicopter pilot, died when his helicopter crashed while trying to fight the fires.

The 37-year-old married father of two had been awarded a NZ Gallantry Star for his bravery while fighting for the SAS in Afghanistan in 2014.

He had his ear shot off while rescuing hotel guests during a five-hour shootout with the Taliban.

Image: More than 1,000 people have been evacuated from 400 homes. Pic: Christchurch City Council Newsline

Philip Duncan, head forecaster at WeatherWatch NZ, told Sky News questions were being raised about what may have caused the fires and whether "there might be something suspicious with it all".

"It is something quite unprecedented in NZ. We don't normally get a lot of big fires, certainly around our cities because our native forest is quite hard to set fire to.

"Christchurch is a very dry part of New Zealand. It has been in a drought for two years now and that is not going to be ending anytime soon.

"It's a very dry, grassy area and lots of sort of scrub and gorse on these hills, fanned by some strong winds which are making things much worse."