Sydney, Dec 17 (IANS): Australian firefighters were battling to save a coal mine and a power station on Tuesday, that have come under threat from a massive bushfire northwest of Sydney.

Already burning through 400,000 hectares of vegetation at Gospers Mountain and the Wollemi National Park, there are now fears the wildfire could spread even further with temperatures in the area expected to reach 46 degrees Celsius in the coming days as an extreme heatwave threatening the nation's east coast, reports Xinhua news agency.

"The heatwave that is coming across the country... add that to strong winds and you've got the worst possible circumstances," New South Wales (NSW) State Rural Fire Service (RFS) Commissioner Shane Fitzsimmons told the media here.

Describing the next five days as the most dangerous the state has seen for "quite some time", Fitzsimmons warned residents in surrounding areas to stay vigilant.

With the bushfire roaring towards the Mount Piper Power Station, which generates around 10 per cent of the state's electricity, fire crews worked tirelessly to protect the facility overnight.

Emergency personnel also scrambled to avoid an environmental disaster as burning embers made way into the Springvale coal mine.

If stockpiles of the commodity were to catch fire, environmental agency Greenpeace Australia Pacific warned it could take weeks to put out the toxic fumes.

According to Centennial Coal, however, the company has reassured the public its stockpiles of coal are well protected behind containment lines.

Since the start of Australia's wildfire season, a total of six people have died and around 720 homes were detroyed, along with approximately 1,600 other structures.