Port Hills fire: 'Impact is the biggest in NZ history'

The Port Hills inferno was so powerful that it was spreading up to 160m every minute at it's peak and was so intensely hot and powerful that nothing could have been done to stop it.

Firefighters are still battling to extinguish hot spots across a 2075ha area of the Christchurch hills, working around the clock for up to 17 hours each to prevent more lives and homes being lost as a result of the inferno.

The fire broke out on Monday night and was at it's peak on Wednesday afternoon when two huge columns of smoke started to build, intensifying the flames and pushing crews to their limit.

"A lot of people are asking why we weren't putting water on it while it was burning away," said Rural Fire sector boss Phil Crutchley.

"We were looking at 100,000 kilowatts of temperature per square metre - any water we put on that just evaporated.

"We just pulled back, it was just too dangerous. There was nothing we could do that would have stopped that."

As a result, homes were lost and other properties damaged - but he made no apology.

The columns had the power of two atomic bombs behind them and there was nothing on earth that could have been done to take the guts out of them.

"It's live first - our lives," he said.

"Property - you can replace. But you can't replace lives."

Incident Controller Richard McNamara said the fire was not the biggest he had fought, but it was by far the most traumatic.

"In terms of impact, yes, it's the biggest in New Zealand history," he said.

"I have faced bigger fires, I have seen more intense fires, but the impact this has had on the community - that's the worst I've experience.

Crutchley said the fire was "gut wrenching".

"It's gut wrenching from the point that we know we've done all we can, but it's not really good enough.

"We wonder what else we could have done - but there is nothing else. There is nothing else we could have chucked at it that would have stopped it, the energy was just too high."

McNamara said it had been a hard week for the crews, but no one was ready to give up.

"It's disturbing when you see someone's home burn down in the space of two minutes. But we've got to swallow that and move on and try to save then next one - and we did."

He said he was extremely proud of his teams, despite criticism from the public about the response to the fire and the management of the incident, and would "go to the grave" knowing everyone had done their jobs well.

One of his men told the Herald: "It's our job, this has to be done".

"We just keep soldiering on, we'll keep working until it's finished."