Media playback is unsupported on your device Media caption Hundreds of homes have been evacuated as the fire nears Christchurch

Hundreds of homes have been evacuated in the New Zealand city of Christchurch as a huge wildfire rages on its outskirts.

One pilot died in a helicopter crash and least 11 homes have burned down.

A state of emergency has been declared in the city and neighbouring Selwyn District and the military has been deployed to help firefighters.

It is unclear what caused the fire, but Prime Minister Bill English has said it "looks a bit suspicious".

He stressed that investigations were continuing.

Media playback is unsupported on your device Media caption Fires are 'contained' but not yet under control. Rain in the north may approach.

Image copyright EPA Image caption Residents have been warned the fires could change direction quickly

On Tuesday, a decorated army pilot was killed when his helicopter crashed as he was tackling the blaze.

Cpl David Steven Askin had been awarded for his bravery while deployed in Afghanistan, for helping save the lives of guests during a hotel siege in Kabul in 2011.

'Don't leave it too late'

The Port Hills fire broke out in two separate places on Monday in the dry hills south of Christchurch, before merging into one blaze which now covers abut 1,800ha.

Image copyright EPA Image caption The fire now covers a 1,800ha area south of Christchurch

More than 130 firefighters have been deployed, along with 14 helicopters and three aircraft brought in from across the South Island.

A total of 400 homes were evacuated by police, but hundreds of other people have also chosen to leave the area.

Image copyright EPA Image caption Helicopter crews have been dumping water on the fires

Police Snr Sgt Ash Tabb warned people that fires can change direction and move quickly, giving little time to escape.

"If you're worried, don't leave it too late - it's better to be safe than sorry."

A Facebook group has been set up by local residents who are offering rooms or properties for people who have left their homes.

Image copyright Reuters Image caption Several fires merged into one

One man told New Zealand's Stuff website that he watched his home burn down from a distance.

"I can't believe it's just caught on fire after it survived the night," said Henry Reese.

On Thursday, Mr English viewed the fire from the air, after which he suggested it could have been started deliberately.

"I've only had a very brief description of the fire starting in two places at about the same time, which to me looks suspicious," he said.

He earlier said the fire was "contained but not controlled", but that the local community "knows how to stick together when things are difficult".

With smoke spreading across the city, the council has issued a warning to residents to see a doctor if they experience breathing difficulties.