The study, prepared by government scientists and the weather bureau for the independent Climate Institute, noted that bushfires are an inevitable feature of the Australian landscape.

But it warned they had already become more fierce in recent years, with fire weather intensity rising 10 to 40 percent since the 1980s and 90s.

The report predicts that the intensity of bushfires in Australia will jump by up to 30 percent by 2050 under the worst global warming scenarios.

And it adds that the number of days each year when there is an extreme risk of fire could soar 65 percent by 2020 and up to 300 percent by 2050.

"The number of very high and extreme fire-weather days is projected to increase in all scenarios," it said.

The largest changes are expected in the state of New South Wales where Sydney is the capital, while the southern island state of Tasmania will have the least.

The report also expands current fire risk ratings to include two more unofficial fire danger levels -- "very extreme" and "catastrophic".

"Climate projections indicate very extreme and catastrophic fire danger levels may become much more common," it said.

"With high global warming, "very extreme" days may occur twice as often in Australia by 2020, with a four or five-fold increase predicted across much of southern and eastern Australia by 2050."

The report also warned of an increase in the risk of injury and deaths, a prolonged fire season and the destruction of ecosystems.

The Climate Institute, which works to raise awareness about climate change, said unless rising pollution from the greenhouse gases blamed for global warming was reversed, Australia's fire weather was set to spiral dangerously upwards.

Firefighters said they were concerned there will be a marked increase in the number of blazes which are uncontrollable.

"It reinforces our message that there will be times when no force known to mankind can suppress these bushfires," chief officer with the South Australian Country Fire Service, Euan Ferguson, told ABC radio.