400ha fire at conservation park in Clarence Valley near Kaikōura

Helicopters working at the scene of the Clarence Valley fire. Photo / Supplied

Investigations into a large blaze at a conservation park in Marlborough are expected to start today.

Firefighters had the fire, which had burnt through about 400 hectares, contained on Thursday afternoon at the Ka Whata Tu O Rakihouia Conservation Park in Clarence Valley.

The fire began at about 6pm on Wednesday and at its peak, nine helicopters were in the air.

A FENZ spokesman said they are looking to get an investigator into the park to examine its cause.

DOC has confirmed that the newer Goose Flat Hut suffered extensive damage, while the nearby historic hut is unscathed.

Local farmworker Lance Godfrey said he could see the fire glow across the night sky.

"It's gone, toasted. it's just a pile of corrugated iron really. It's been very hot the last two days, it's 31 degrees today."

An infrared camera is planned to fly over Saturday morning to check for any hot spots.

Six people were evacuated from the area on Wednesday.