(AFP) - Australians on Sunday counted the cost from a day of catastrophic bushfires that caused "extensive damage" across swathes of the country and took the death toll from the long-running crisis to 24.

Hundreds of properties were destroyed and one man died trying to save a friend's home in the severe conditions -- among the worst in Australia's months-long bushfire crisis.

In the country's southeast the skies turned black and ash rained on isolated communities.

"We're in uncharted territory," New South Wales state Premier Gladys Berejiklian said.

"We can't pretend that this is something that we have experienced before. It's not," she said.

"Several townships who never ever experienced a threat of bushfire were at threat of being completely wiped out."

The severity of the crisis -- which has seen an area roughly double the size of Belgium burnt -- saw Prime Minister Scott Morrison announce the largest military call-up in living memory, mobilising up to 3,000 reservists to assist exhausted volunteer firefighters.

But in rare public criticism, the New South Wales rural fire service chief said he only found out about the deployment from media reports -- the latest criticism of the prime minister's response to the disaster.

"I was disappointed and frustrated in the middle of one of our worst days with massive dislocation and movement of people," Shane Fitzsimmons said.

"We spent a fair amount of the day yesterday trying to seek clarity."

Fitzsimmons -- whose own father was killed firefighting -- has been the face of the crisis in Australia's most populous state, tearfully informing the public about the death of volunteer firefighters and pinning a medal on one of their toddlers in a haunting image.

Tens of thousands of volunteer firefighters have been hailed in Australia and across the world for their unrelenting battle against the blazes.

Queen Elizabeth II on Sunday sent a message of condolence of the governor-general, her representative in Australia, saying she was "deeply saddened" by the fires, and thanked the emergency services "who put their own lives in danger" to help communities.

Celebrities have pledged or raised millions of dollars to support firefighters and fire-affected communities, including US singer Pink who tweeted Saturday that she was donating US$500,000.

Australian actress Nicole Kidman matched that pledge.

"Our family's support, thoughts and prayers are with everyone affected by the fires all over Australia," she posted on Instagram. "We are donating $500,000 to the Rural Fire Services who are all doing and giving so much right now."

- Easing conditions -

Sunday brought milder conditions including cooler air and some rainfall in New South Wales and neighbouring Victoria state -- where firefighters also battled huge infernos spurned on by winds and lightning strikes.

That will give authorities opportunity to get fires under control and take stock of the damage.

But some communities were still under threat from out-of-control blazes, particularly in and around the town of Eden in New South Wales near the Victorian border.

"Visibility was down to about 50 metres, if that, and we had lots of debris falling out of the sky and a lot of white ash," John Steele, 73, who was evacuated with his wife from their rural property north of Eden late Saturday, told AFP.

"The sky is still red" he added, "we're not out of the woods yet."

In Cooma in inland southern New South Wales, the fire crisis turned into a flood disaster when a large tower carrying 4.5 million litres of water swept away cars and filled homes with mud.

"First bushfire and now flood, back-to-back disasters," a shaken resident who asked not to be named told AFP.

Australia's capital Canberra was ranked as the city with the poorest air quality in the world on Sunday by Air Visual, an independent online air quality index monitor, amid a severe haze caused by the fires.

Galleries and other buildings were closed safeguard public health.

In some rural areas police patrolled streets amid reports of looting and break-ins in bushfire-affected areas.

While bushfires are common in Australia's arid summers, climate change has pushed up land and sea temperatures and led to more extremely hot days and severe fire seasons.

© Agence France-Presse