Australian firefighters continue to battle a series of massive bushfires burning in mountains west of Sydney before the return of forecasted dangerously hot, windy weather.

Shane Fitzsimmons, New South Wales Rural Fire Service Commissioner, said on Tuesday that about 60 fires were still burning, with the largest and most dangerous in the Blue Mountains, around 100km west of Sydney.

Thousands of firefighters, hundreds of fire engines and 90 aircraft were battling the blazes, which have burned through more than 120,000 hectares and have a perimeter of 1,600km, he said.

"You are talking about some of the most beautiful, scenic country in the world, but it is an awful challenge for fire fighting and fire management," Fitzsimmons said.

Australia bushfires rage out of control

Air pollution in parts of Sydney surged on Tuesday to dangerously high levels as smoke and ash blanketed the city.

Efforts had been focused on back-burning vegetation to reduce the fuel available for the fires, bulldozing containment lines, and merging two large fires into a single blaze that would be easier to control.

More than 200 homes have been destroyed in New South Wales (NSW) state since last Thursday, when fires tore through farm and bush land and scattered communities on Sydney's outskirts, razing entire streets.

The insurance council of Australia said claims of more than A$93m ($90m) were expected to grow and the NSW government has declared a state of emergency.

One man died of a suspected heart attack last week while trying to defend his home from a fire north of Sydney.

Elsewhere in the area, Australian police arrested two boys suspected of starting fires in the Hunter Valley.

With dry weather and a massive land area, Australia is particularly prone to bushfires. In 2009, the Black Saturday bushfires in Victoria state killed 173 people and caused $4.4bn worth of damage.

New South Wales has just experienced the warmest September and warmest 12 months on record, according to the Bureau of Meteorology.

A storm cell was moving towards the region, while strong, dry westerly winds with 80kmph speeds and temperatures in the mid-30C range were predicted for Wednesday.

Christiana Figueres, executive secretary of the United Nations Framework Convention on Climate Change (UNFCCC), told CNN that bushfires are linked to man-made global warming that Tony Abbott, Australia's new prime minister, once described as "absolute crap".

Source: Agencies