BRISBANE • Australian firefighters are struggling to control a massive bush fire that had already destroyed 40 per cent of the Unesco world heritage listed Fraser Island before a heatwave hit yesterday.

The fire on the world's largest sand island, off Australia's east coast, has been raging for more than six weeks and is consuming large swathes of the island's unique forests.

Temperatures were set to peak at 34 deg C yesterday as a heatwave sweeps across the region, raising concerns that hotter conditions will further fuel the blaze.

"The vegetation on Fraser Island is extremely dry and because it's so dry it's therefore very easy to ignite," incident controller James Haig told Agence France-Presse.

About two-thirds of Queensland state, including Fraser Island, is currently gripped by drought.

A recent report from the nation's top science and meteorology agencies says climate change is fuelling more extreme droughts, bush fires and cyclones in Australia - a situation which will only worsen as temperatures continue to rise.

Firefighters are not only battling "very challenging weather conditions", Mr Haig said, but are stymied by limited access to the blaze in the island's remote north.

Queensland Parks and Wildlife Service said the fire was burning on two fronts across 74,000ha - or 42 per cent of the island - but was not threatening properties.

However, as the fire has inched closer to settlements in recent days, the authorities have banned new visitors from travelling to the popular holiday destination, and restricted ferry services.

Mr Haig said as many as 10 water bombing aircraft had been deployed to fight the fire, including some tasked with protecting culturally significant Aboriginal sites.

Planes dropped about 250,000 litres of water last Saturday alone, although Mr Haig said these efforts "will not stop the fire" but merely slow its progress.

"We really need rain and we're unfortunately not likely to receive it for some time," he said.

The Queensland Fire and Emergency Service has imposed a seven-day fire ban in the area starting late yesterday, as firefighters prepare for an extended stretch of difficult weather conditions.

Fraser Island was listed as a world heritage site for its rainforests, freshwater dune lakes and complex system of sand dunes that are still evolving.

Mr Haig said firefighters were trying to balance their management of the blaze - which is believed to have been sparked by an illegal campfire - with the need to avoid inflicting any further environmental damage.

More than 50 bush fires were burning across New South Wales state yesterday, where a return to heatwave conditions is forecast for today.

AGENCE FRANCE-PRESSE