An entire koala population in Port Stephens could be wiped out after a fire devastated their habitat near Port Stephens, an animal rescue group fears.

An estimated 16 hectares of the Mambo Wetlands, north of Newcastle, was scorched on Monday night, according to Port Stephens Koalas.

The reserve is about 40 per cent of the vital koala habitat.

The blaze broke out near the Salamander Bay shopping centre about 6:30pm and dozens of firefighters spent the night backburning to protect homes.

It burnt away more than 80 hectares of swampy scrub, which made access difficult for fire crews.

The fire flared up to a watch and act level at 3:00am, but weather conditions eased in the early hours and the blaze was brought under control.

An injured koala clings to a tree in the Mambo Wetlands. ( ABC News: Colin Kerr )

Carers from the rescue group today surveyed the damage and fielded calls about stranded and injured wildlife.

Simone Aurino, senior carer at Port Stephens Koalas, said the reserve was one of the most important areas in the Tomaree Peninsula.

"It has a viable breeding population and its central to all the other habitats," she said.

"It's a really, really essential habitat."

Ms Aurino said the blaze would lead to significant flow-on effects which may not be known for some time.

"It has the potential to wipe out the population in this area, it's really quite devastating," she said.

"The habitat's been changed, so the animals are going to move.

Animal rescuers fear the local koala habitat will be wiped out after the blaze. ( ABC News )

"They're going to move across roads, we're going to have animals in backyards having encounters with dogs, we're going to have them on the roads getting hit by cars."

The group managed to rescue one distressed koala seen clinging to a blackened tree.

Volunteer Ben Van Der Wijngaart said the animal was "obviously very traumatised" and was reluctant to move, which would indicate burnt paws.

"Anybody reacts emotionally to it," he said.

"Sometimes you've got to irritate it further to help it."