Marlborough blaze still burning fiercely

A large forest fire in Marlborough is still burning fiercely, firefighters say - with its cost predicted to be at least $3 million.

Helicopters with monsoon buckets were still working in rotation to contain the fire this afternoon, with a large number of ground crews assisting the effort.

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Marlborough Principal Rural Fire Officer Richard McNamara said the fire was very aggressive, moving swiftly through forestry harvest debris, mature pine trees and some native scrub in the Waikakaho Valley, north-west of Blenheim.

The fire had threatened several properties but losses had so far been confined to timber, vehicles and forestry equipment, he said.

He estimated property losses would be worth between $2m and $3m, with firefighting costs likely to be over $1m.

Police have been advising people in the Waikakaho Valley to leave, and to stay away overnight.

Half of the 24 houses in the valley have been evacuated but police said about 12 residents had chosen to stay at their own risk.

Some of those who decided to stay said flames had reached within metres of their homes.

Incident team controller Rob Hands told Checkpoint they were keeping in close contact with those who had chosen to stay.

The weather was not on the firefighters' side with more high winds forecast, he said.

In a weather warning shortly before 1pm, MetService said severe northwest gales of 130km/h - and possibly up to 160km/h in some areas - were expected on Friday.

Cause of fire not yet known

Five families were evacuated from their homes yesterday, and about 20 houses were without power overnight.

About 60 firefighters were battling the fire this morning, with others on their way from Nelson and elsewhere to help.

"We've got a little bit of opportunity right through the early part of the morning to build in some containment lines, and that's exactly what we'll be trying to do," Mr McNamara said in another interview earlier today.

"Essentially, it's just scrapping down to earth using bulldozers and diggers to form a clear earth line between active fire and fuel that is unburnt."

People living near the valley should still be prepared to evacuate at any time, he said.

The cause of the fire remained unclear, but Sue Huddleston - the co-owner of a forestry block near the blaze - said she believed it started on a forestry skid site.

Mrs Huddleston said their forestry block - which occupied more than a couple of hundred hectares of land - was about eight or nine years from harvest.

They could only hope the block remained out of the fire's path, she said.

Meanwhile, the SPCA has been helping with shelter and transport for any animals affected by the fire.