The blazes, which have swept across parts of Victoria state, have claimed 173 lives. Hundreds of people have been injured, some critically.

Residents in many areas are still on alert as more than a dozen fires continue to burn uncontrolled.

Some fires are being treated as arson, which Prime Minister Kevin Rudd said amounted to "mass murder".

Detectives have sealed off a number of sites, including the devastated small town of Maryville, as possible crime scenes.

Victoria State Premier John Brumby has announced that a royal commission will examine all policies on dealing with fires.

Visiting affected areas on Monday, he said: "We have had whole communities just completely wiped out, completely obliterated, by what people would describe as literally a fireball that just came over the hills and devoured everything before them.

"It's the largest natural disaster in our state's history and Australia's history."

Mr Brumby warned that the death toll would rise as fires continued to rage in some areas.

"There is a huge effort to get them under control (but) tragically we will have more deaths later this week," he said.

Several communities are on alert, with residents warned to watch out for embers blowing in from bush fires.

Rescue teams are expected to find more victims as they scour isolated communities where residents were trapped - some in their cars.

A record heatwave and changing wind directions on Saturday helped fan the flames, which destroyed more than 750 homes, left 5,000 people homeless and burned 850 square miles (544,000 acres) of land, the Victoria fire service said.

Medical officials said emergency departments across the state had dealt with more than 450 people injured by the bushfires since Saturday.

At the Alfred Hospital in Melbourne, the burns unit was treating 21 people with at least 30% burns on Monday night. Nine of those people were in intensive care.

"The classic burn patterns that we are seeing is mostly due to people who have been forced to run through flames or have been exposed to extremely high radiant heat temperatures," Director Dr Heather Clelland said.

An emergency doctor in the unit, Dr de Villiers Smit, said the injuries he was seeing were worse than those he had dealt with after the Bali bombings.

Despite cooler conditions than the weekend, officials in Victoria have issued a series of alerts warning of flare-ups.

Shifting winds threatened to send the fires beyond containment lines hacked out by fire crews.

The BBC's Nick Bryant in Victoria says the mood at the state's relief centres is sombre, with many people searching for loved ones among the survivors.

Australian media is reporting survivors' accounts of how they fled walls of fast-advancing flames.

From Kinglake - where at least 35 people died - resident Thomas Legrary described finding a neighbour with up to 50% burns on his body.

They put him in a swimming pool to keep him cool and he was later taken to hospital.

Sonja Parkinson and her young son escaped the inferno in Kinglake by fleeing their home and huddling under a damp blanket in a puddle in a creek.

She said flames roared overhead "like a jet engine" and she was convinced they would die.

"The two front rooms were ablaze. I couldn't see," she told The Australian newspaper. "We went down to the creek and we hid. This little one was so brave under the blanket."

Prime Minister Kevin Rudd has announced an aid package of A$10m ($7m, £4.5m).

Asked about suspicions that arsonists were responsible for at least some of the fires, he said: "There are no words to describe it other than mass murder."

Victorian police are expected to reveal details of a task force set up to investigate the cause of the bushfires, Australia's ABC News reported.

The Australian Red Cross, which has about 400 volunteers working in Victoria, has launched an appeal for donations