A fire truck is dwarfed by flames from a bushfire about 125 kilometres west of Melbourne on Saturday. (Associated Press)

At least 35 people have died as a result of wildfires that are sweeping across southeastern Australia, officials confirmed.

Victoria state police spokeswoman Sarah Campbell said that by Sunday local time, official had found bodies at 12 different sites across the zone that was blasted by the wildfires the day before.

Authorities are still trying to reach several other areas hard-hit by the fires, Campbell said, and the death toll could rise.

Authorities said as many as 40 people may have perished in fires fanned by high temperatures and strong winds in three states.

As police announced a higher death toll, they said more bodies could still be inside some of the hundreds of destroyed homes.

Among the victims were six people who died in a single vehicle in the town of Kinglake in Victoria state.

"The whole township is pretty much on fire," Peter Mitchell, a resident of Kinglake, told the Australian Broadcasting Corporation. "There was no time to do anything ... it came through in minutes."

More than 30,000 firefighters were struggling Saturday night to make headway against the largest of about a dozen fires in Victoria.

"The fires are just too hot to approach on foot, and choppers can't find their targets because of smoke," said freelance reporter Tim Stackpool, who has been following the story from Sydney.

Temperatures have been as high as 47 C, but forecasters predict they will dip to a low of 27 C by Sunday.

"Tomorrow should be last gasp of the heat wave, which has typically seen temperatures in the high 40s. It should cool down the rest of the week," Stackpool told CBC News.

However, as a cool front moved through the hard-hit Gippsland region, along with it came wind changes that pushed the fires in new and unpredictable directions.

With files from the Associated Press