The death toll from Australia's rampaging wildfires has risen to 171 as police began investigating claims that some were started deliberately.
An emotional prime minister Kevin Rudd said if arson was proved it was "mass murder".
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Mr Rudd, visibly upset during a television interview, reflected the country's disgust. "What do you say about anyone like that?" he said. "There's no words to describe it, other than it's mass murder."
The country's top law officer, attorney general Robert McClelland, said that people found to have deliberately set fires could face murder charges.
More than one dozen fires are still burning uncontrollably across Victoria, although conditions are much cooler than on Saturday, which saw record-high heat and winds of up to 60 mph.
At least 750 homes were destroyed and 850 square miles of land burned out.
Officials said both the death toll and destruction would almost certainly rise as they reached deeper into the disaster zone, and forecasters said temperatures would rise again later in the week, posing a risk of further flare-ups.
In a sign of the nationwide impact of the tragedy, Parliament suspended its normal sessions to hear condolence speeches from MPs. The voices of many quavered with emotion. Some called it Australia's worst peacetime disaster.
More than 4,000 people registered with the Australian Red Cross, which posted lists of names at some 20 emergency relief centres. At one centre in Wittlesea survivors scoured the lists looking for missing relatives.
Victoria Police Commissioner Christine Nixon said investigators had strong suspicions that at least one of the deadly blazes - known as the Churchill fire after a ruined town - was deliberately started. And it could not be ruled out for other fires.
Australia's previous deadliest fires were in 1983, when blazes killed 75 people and destroyed more than 3,000 homes in Victoria.
State Department of Sustainability and Environment spokesman Geoff Russell said: "Hell in all its fury has visited the good people of Victoria," Mr Rudd said.
"It's an appalling tragedy for the nation."
The town of Marysville and several hamlets in the Kinglake district, both about 50 miles north of Melbourne, were utterly devastated.
At Marysville, a winter tourism town that was home to about 800 people, up to 90% of buildings were in ruins, witnesses said. Police said two people died there.
Thousands of exhausted volunteer firefighters were still battling about 30 uncontrolled fires tonight in Victoria, officials said, though conditions had eased considerably. It would be days before they were brought under control, even if temperatures stayed down, they said.
A Number 10 spokesman said: "The Prime Minister spoke to Kevin Rudd this morning to extend our sympathies to the Australian people, especially those families who have been affected by this tragedy.
"He praised Kevin Rudd's leadership at this very difficult time, and said that the UK stood ready to provide any assistance that the Australian Government wanted."