Bushfires have destroyed huge tracts of the Australian countryside.
John Brumby, the premier of the hard-hit state of Victoria, said many of 20 fires burning Wednesday were suspected to have been started by arsonists -- an act described earlier by Prime Minister Kevin Rudd as "mass murder."
"There seems little doubt these were deliberately lit -- a number of them last night," Brumby said on national television.
"I think words escape us all when it comes to describing deliberate arson."
Seven Network reporter Sarah Cumming said two major fires blazing west of Melbourne at Healesville and Bunyip State Park were in danger of joining up despite being 18 kilometers apart.
Watch firefighters continue to struggle in tackling the blazes »Several fires started by lightning between the two blaze fronts were exacerbating the situaion, she said.
The toll of the past week's fires stands at more than 500 people injured, nearly 1,000 homes destroyed, thousands left homeless and at least 365,000 hectares (901,935 acres) of the Australian countryside burned black, authorities said.
Fires, thought to have been started by arsonists have devastated the towns of Marysville and Kinglake. As many as half the homes in Kinglake have burned to the ground, police say. iReport.com: 'Thank God we were spared'
The death toll is expected to rise. In Marysville, officials warned that as many as 100 people, or one-fifth of the town's population, might be dead, with many bodies believed to be still buried under debris.
Photos: Bushfires leave path of destruction »Likely to add to the fatality figure was the discovery by forensic scientists that some skeletal remains initially thought to be single bodies were actually two people fused together by searing temperatures.
As efforts to help those affected by the wildfires gather pace, tent cities have sprung up in Whittlesea, just north of Melbourne. Relief agencies have pitched camps for those forced out of their homes.
Many fire victims have grown increasingly frustrated, kept from returning home -- or to what is left of their homes -- by authorities because of safety concerns.
Fires were Wednesday threatening a gas plant and a reservoir supplying Melbourne, Cummings added. She said firefighters were counting on three days of relative calm weather before high winds were expected to fan flames again.