Sydney  - Half the forest fires in Australia are started intentionally and most arsonists get away with their crimes, an Institute of Criminology report released Sunday showed.

The institute put the damage bill for arson attacks at 1.6 billion Australian dollars (1 billion US dollars) a year.

The report recommended that areas vulnerable to bushfires be out of bounds when arsonists may strike.

Arsonists pick their moment: the hottest temperatures, the strongest wind to fan the flames, the driest patch of forest - and whoosh!

In the past 30 years, about 250 people have died in bushfires. Hundreds of homes have been razed. Thousands of livelihoods have gone up in smoke. Millions of animals have perished.

Attorney-General Robert McClelland said arsonists are rarely caught and convicted.

"We need to look at a greater coherence in the sentencing strategy," he told national broadcaster ABC.

In forest fires four years ago, seven people were killed, 500 houses razed and 3 million hectares of forest burned - an area three times the size of Britain. (dpa)