At least 12 homes were damaged or destroyed after a wildfire swept through a small coastal area north of Sydney, Australia, officials said on Saturday.

The wildfire broke out at Koolewong, on the New South Wales Central Coast following extreme fire danger conditions in the eastern and central parts of the state.

Aerial footage showed multiple homes on fire as firefighting helicopters worked to extinguish the flames.

There were no reports of injuries at this stage, New South Wales Premier Chris Minns said.

Over 75 wildfires including 19 that are not contained were burning across New South Wales, Minns told reporters in Sydney.

Hundreds of firefighters supported by aircraft and fire trucks were fighting the blazes, he added.

Temperatures in Sydney topped 40 degrees Celsius (104 degrees) and heatwave warnings were issued across multiple parts of the New South Wales state.