Media playback is unsupported on your device Media caption "It was a result of a detonation on the live firing range" - Shane Fitzsimmons, New South Wales Rural Fire Service Commissioner

A plane fighting bushfires in the Australian state of New South Wales has crashed, killing its pilot, as the military faced criticism for starting one of the major fires.

The water-bombing plane crashed near Ulladulla, south of Sydney.

Meanwhile the military said it was co-operating with a fire services probe that found an exercise using live ordnance started the State Mine fire.

NSW has been battling bushfires for days, amid high temperatures.

Officials have yet to release the identity of the pilot, who was the only person aboard the aircraft. His family has been informed of his death.

"It's a tragedy for the fire-fighting community," said NSW Rural Fire Services Commissioner Shane Fitzsimmons.

'No intention'

Thousands of firefighters have been mobilised to tackle the fires, and on Wednesday the state came through what officials had said would be a very dangerous day because of weather conditions.

Thursday brought cooler weather but more than 60 fires are still burning. Worst-hit has been the Blue Mountains area, to the west of Sydney, where many homes have been destroyed and some residents evacuated.

The State Mine blaze, near the Blue Mountains town of Lithgow, was seen as a serious cause for concern earlier in the week.

Media playback is unsupported on your device Media caption NSW Police Superintendent Joe Cassar: Rescue teams at crash scene

Fire chief Shane Fitzsimmons said an investigation had found it was ignited by live ordnance.

"It wasn't deliberate, it was a side-effect of a routine activity ... and clearly there was no intention to see fire start up and run as a result of that activity," he said.

Acting Defence Minister George Brandis said the military "take this issue very seriously and continue to fully co-operate with the NSW authorities, including the NSW Police, who are investigating the fire".

Acting Chief of Defence Air Marshall Mark Binskin subsequently offered an apology, saying: "What I do know to date is it was an explosives activity, it was a demolition activity in support of our people that train for operations around the world".

Blue Mountains Mayor Mark Greenhill said the military should have known better.

"I would have hoped on a day like that which was a dry day, a hot day, with the winds, the Australian military would have known it wasn't a good time to be igniting.

So far the NSW fires have destroyed more than 200 homes and left one man dead.

How eucalyptus trees help bushfires to spread

Ninety percent of Australia's forests are eucalyptus trees that are adapted to bushfires. Eucalyptus leaves are rich in flammable oils and many varieties also have trunks that have evolved to burn quickly and later sprout new growth from buds in the bark (right)

The fastest-moving and most dangerous part of the fire is known as the "head". Areas ahead of the fire are warmed as it approaches and flying embers blown by the wind spark "spotfires", which cause it to leap further ahead

Fires travel faster uphill than downhill, as the heat and smoke rise, heating areas higher up the hill. Wind currents also tend to blow uphill, pushing the flames further. Burning embers may roll downhill, starting new fires

Meanwhile, former US Vice-President Al Gore has entered the debate over climate change, calling on Australian Prime Minister Tony Abbott not to repeal the carbon tax.

On Wednesday, Mr Abbott accused the UN climate chief, Christiana Figueres, of "talking through her hat" when she described bushfires as "absolutely" linked to climate change.

Mr Gore told ABC News: "Bushfires can occur naturally, and do, but the science shows clearly that when the temperature goes up, and when the vegetation and soils dry out, then wildfires become more pervasive and more dangerous.

"The meaningful way to solve this crisis is to put a price on carbon, and in Australia's case to keep a price on carbon," he said.

Mr Abbott is working to repeal a tax on carbon introduced by the Labor government that charges Australia's top 300 polluters for their emissions.

He says the tax cost jobs and drove energy prices up, and intends to replace it with a subsidies scheme.