Areas of Matakana Island are still burning underground as firefighters worked until dark to keep hotspots under control.

The fire began on Saturday night and burned through about 37ha of scrub and pine slash on the island.

Firefighters spent their Christmas Day on site battling the blaze.

At 9.30am yesterday, Fire and Emergency New Zealand district commander Jeff Maunder said the fire was “100 per cent contained”.

“But there are some weak points we are working on.”

Firefighters continued working on Matakana Island until dark on Monday night. Photo / Supplied

At 7.30pm yesterday, Maunder said firefighters would continue working until dark when two crews would take over monitoring the fireground.

“Active firefighting will resume in the morning with crews on the ground and two helicopters waterbombing. It’s likely that operations will continue until at least Wednesday.”

Fire and Emergency’s specialist drone crew was working on Matakana Island overnight, using thermal imaging to identify hotspots around the perimeter of the fireground so that firefighters will be able to target them tomorrow.

Maunder said the fire was “complex”, with areas where it was burning underground — for example in the root systems of large trees — as well as in the “duff layer” of partly decayed organic material on the ground and in living vegetation.

The fireground on Matakana Island at 6am on Christmas Day. Photo / Supplied

“There are pockets of vegetation and tree stumps that are still smouldering and could reignite if not fully extinguished.”

Maunder said people in Tauranga and along the coast could still expect to see and smell smoke from the fire over the next day or so.

He thanked Matakana residents who had dropped off baking and other supplies for the firefighters, and also the local ferry operator who had made extra trips to make sure that crews, vehicles and equipment could cross to and from the island.

“We really appreciate the support from the community. Everyone working on this fire has given up Christmas Day with their families. We’ve made sure they’ve had some Christmas treats today — they’re working hard — and it’s also good to know that the locals are right behind us.”