A drone has been spotted flying in the Wakefield area where helicopters are battling to extinguish a monster fire near Nelson.
Police received a report a drone was flying in the area shortly before 11am on Thursday.
Anyone operating a drone in the area should stop immediately, they say.
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"Drone activity has the potential to stop all helicopters responding to the emergency fire situation," a police spokesperson says.
"This is extremely dangerous and our priority is to ensure the helicopters can continue with their work."
Around 400 people have been evacuated from 182 properties as the fire that broke out in the Pigeon Valley area on Tuesday rages on.
Civil Defence says one house has been destroyed in the blaze and they are checking other properties.
The fire is estimated to have burnt around 1900 hectares. Firefighters have monitored the massive blaze overnight and say it hasn't spread significantly. The fire at Rabbit Island has now been contained.
Prime Minister Jacinda Ardern arrived in Nelson on Thursday morning and announced the Government's support for the Tasman region along with Minister of Civil Defence Kris Faafoi and Minister of Agriculture Damien O'Connor.