SYDNEY (AFP) - Australian police said many people remained unaccounted for on Monday but no deaths had yet been recorded in fire-ravaged Tasmania state, as the rest of the nation braced for a dangerous heatwave.

Prime Minister Julia Gillard toured the shaken southern island, where more than 100 homes were razed in catastrophic heat and wind conditions by fast-moving blazes that continued to burn across the state.

Tasmanian police said they had searched 245 properties in the worst-hit areas by Monday morning including 90 badly damaged or destroyed buildings.

"The preliminary screening search has discovered no deceased people at this stage," police said.

About 100 people were reported missing following the fires and police said many people remain unaccounted for, although they cautioned that cross-referencing of almost 2,000 evacuees was continuing.

Initial investigations suggested that the fires ignited accidentally and "there is no indication at this stage that any of the fires in Tasmania were started intentionally", police added.

Residents who narrowly escaped the fire front described darkness as it approached. "As the fire came through, what had been a really bright red sky turned absolutely pitch black," survivor Del Delagarno told ABC radio.

Her home was one of just six in the seaside town of Boomer Bay still standing.

"It was as if it was the darkest midnight you've ever seen - it was absolutely horrendous," she added.

Emergency crews in Tasmania and several other Australian states were battling to contain scores of blazes that started in a heatwave last week before conditions worsen again, with scorching temperatures predicted in coming days.

In New South Wales (NSW), Australia's most populous state, the mercury was expected to hit near-record levels, with temperatures in Sydney forecast to peak at 43 deg Cel on Tuesday.

NSW Rural Fire Service Commissioner Shane Fitzsimmons said the weather would bring the state's worst fire danger for "many, many years", with catastrophic conditions expected in some areas.

"Given we've got this plentiful supply of fuel, particularly grassland fuel, across much of the very bad weather areas, fires will start very easily and spread very quickly," he said.

"We've got awful conditions coming our way and people need to be prepared." In neighbouring Victoria state, scene of the deadly Black Saturday firestorm that killed 173 people in 2009, hot and windy conditions were expected on Tuesday, with very high and severe danger ratings for much of the state.

The 2009 Victoria inferno, which destroyed more than 2,000 homes, was Australia's worst natural disaster of modern times.

Blazes were also reported in the Australian Capital Territory, South Australia and Queensland states.

Wildfires are a fact of life in the vast but sparsely populated arid continent, particularly in the hot summer months between December and February.