But warmer weather linked to global climate change and a spate of big fires in recent years is convincing experts of an altered pattern, and has triggered intensive efforts to meet the threat.

"There is a clear trend - hotter weather in Australia, more frequent bushfire seasons, more frequent serious bushfire incidents," said Kevin O'Loughlin, chief executive of the Bushfire Cooperative Research Centre.

Last year was Australia's hottest year, the Bureau of Meteorology said this week, blaming global warming as the most likely explanation.

At least three serious fires raged over southern Australia over the past five years, gutting more than 530 homes in Canberra, killing nine people in South Australia and destroying an area nearly three times the size of Britain.

Fires broke out across southeastern Australia last weekend as temperatures in some areas rose above 44 degrees Celsius (111 F).

"If you compare that with 30 or 40 years ago, that's a major shift in the frequency and intensity of bushfire seasons," said O'Loughlin.

To combat the increased threat, firefighters and government agencies are studying issues ranging from arson, cities expanding into bushland fringes, the movement of city dwellers to the country, national park management and how to build safer homes.

Best estimates suggested up to half of all bushfires were deliberately lit, said Matthew Willis, research analyst at the Australian Institute of Criminology, although the figure could be much higher near urban areas.

While many fires were started by children or vandals, these were often small and quickly brought under control. Serial arsonists lit fewer fires but were likely to cause more damage.

"People who go out and put effort into lighting fires do often show quite a lot of knowledge about what they are doing," said Willis, pointing to the use of incendiary devices.

Profiling aims to help police track down arsonists, and suggested firelighters - almost always males - are looking for excitement, craving attention or recognition or expressing anger.

Police in several Australian states have started to monitor known arsonists over the bushfire season, while jail sentences have been increased in recent years for offenders.

"If you can increase the likelihood of people being caught that certainly works as a deterrent, together with increased penalties," said Willis.

National park management is a major issue, pitting environmentalists, who want to keep parks pristine, against those urging controlled burn-offs to keep down undergrowth.

Even an ageing population has implications for bushfires.