A wildfire has destroyed ' title=' wildfire has destroyed '>wildfire has destroyed at least 11 homes and forced the evacuation of more than 1,000 people in New Zealand's Christchurch city, authorities said on Thursday.

Around 450 homes were officially evacuated on Thursday morning.

A state of emergency was declared in the South Island city and neighbouring Selwyn district late Wednesday as two blazes that had been smouldering for days merged into a single giant fire-front, the New Zealand Herald daily reported.

The emergency claimed the life of a decorated army pilot, David Steven Askin, who was killed on Tuesday when his helicopter crashed while tackling the blaze.

John Mackie, the civil defence controller for Christchurch, said about 130 firefighters on the ground, assisted by more than a dozen helicopters, had stopped the fire from encroaching further into the city.

Prime Minister Bill English took a helicopter flight over the disaster zone and said the blazes may have been deliberately lit.
 

"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 told reporters.

He stressed that the investigations were continuing.

Christchurch City Council said more than 1,800 hectares of land had been torched in the Port Hills, an area of rugged terrain difficult to access to the east of the city centre.

An "evacuation housing" Facebook page was established to offer support to those who have been forced to flee the flames. Hundreds of people quickly flooded the social media page offering beds, blankets and home baking.

The fire "compromised properties" in the Worsley, Hoon Hay Valley and Kennedys Bush roads, and streets in the vicinity of Longhurst Terrace in Cashmere.