Christchurch mayor Lianne Dalziel told Mike Hosking that she was "very worried" for Christchurch.

"We've been going through what's happened overnight, obviously there's been more evacuations so we're looking at 450 properties approximately that have been officially evacuated, with police doorknocking and the army in support as well, so it is very serious."

She said people have been reporting seeing the fire very close to their properties near Port Hills.

"It looks as if up to seven properties have been affected by the fire, it's difficult to say until light arrives to get a full handle on how many properties that have been destroyed."

Dalziel said the blaze was a "difficult fire".

"We had two seperate fires, one that started in the Selwyn district, managed as a significant rural fire, then fire erupted on the city side, ultimately the worst fears were realised and the two fires came together yesterday.

"It is close to areas of population, I don't want anyone to diminish that, we do have problems with people rubber-knecking."

She said people need to "stay at a distance" away from the fire.