SYDNEY (REUTERS) - Australian authorities urged nearly a quarter of a million people to evacuate their homes on Friday (Jan 10) and prepared military backup as soaring temperatures and erratic winds were expected to fan deadly bush fires across the east coast.

Temperatures were expected to shoot well above 40 deg C in several parts of the country on Friday, accompanied by high winds, threatening to inflame fires that have already left thousands of people homeless.

In the alpine region on the border of the south-eastern states of Victoria and New South Wales, two fires were poised to merge and create a blaze over almost 600,000ha.

"With so much fire in the landscape, we are going to continue to see fires getting a run on, fires flaring up, for weeks to come," Mr Daniel Andrews, the premier of Victoria, told a televised briefing.

"Even with rain in Melbourne, even with forecast better conditions next week, there is a long way to go in what has been an unprecedented fire event...and, of course, we know that we have many weeks of the fire season to run."

He urged residents to stay on high alert and leave the community "if you are told to".

Mr John White, mayor of East Gippsland, an area that was ravaged by fires on New Year's Eve, told Reuters that residents were on the move: "People aren't taking any chances."

Authorities sent emergency texts to 240,000 people in Victoria, telling them to leave. People in high-risk regions in New South Wales and South Australia were also urged to think about leaving, but officials did not say how many.

Prime Minister Scott Morrison said he had given instructions to the military so "that they are to stand ready to move and support immediately" as firefighters battle 150 blazes across the country.

Authorities said conditions would continue to deteriorate across Victoria as heavy winds whip the state, grounding military helicopters that had been helping with evacuations and supply drops.

Since October, 27 people have been killed and thousands subjected to repeat evacuations as monster and unpredictable fires scorched more than 10.3 million ha of land, or an area the size of South Korea.

Emergency services minister Lisa Neville said some communities had been provided with large containers of satellite phones, baby formula, food, nappies, and torches in case they are cut off.

Campaigners protested in Sydney and Melbourne on Friday as part of a wave of demonstrations planned in major world cities, to spotlight concerns about Australia's climate change policies.

Australia's wildfires have dwarfed other catastrophic blazes around the world. The combined 2019 fires in California, Brazil and Indonesia still amounts to less than half the burnt area in Australia.

Australia's government has maintained there is no direct link between climate change and the devastating bush fires, a stance that has prompted campaigners to plan worldwide protests for Friday.

"We don't want job destroying, economy destroying, economy wrecking targets and goals which won't change the fact that there are bush fires or anything like that in Australia," Mr Morrison told 2GB Radio, referring to calls for the government to commit to higher carbon emissions cuts.

The following are some highlights of what is happening in the bush fire crisis:

* Of 153 fires ablaze across New South Wales (NSW), about 39 were uncontained. Three blazes were in the "watch and act" category, with the rest at the "advice" level, the lowest alert rating

* Neighbouring Victoria had 38 fires, one of which was so severe that evacuation orders were issued. Eight more are at an emergency level.

* Westpac estimated total bushfire losses to date at about A$5 billion (S$4.6 billion), higher than the 2009 bushfires in Victoria but smaller than the Queensland floods in 2010/11. It forecast a hit of 0.2 per cent to 0.5 per cent on gross domestic product.

* Prime Minister Scott Morrison said he had told the military "to stand ready to move and support immediately".

* Australia's alpine resorts have dusted off winter snowmaking machines to blast ice-cold water onto dry ski slopes as fires threaten the Snowy Mountains region.

* The Insurance Council of Australia increased its estimate of damages claims from the fires to more than A$900 million, with claims expected to jump further.

* Health officials in New South Wales urged extra precautions to avoid heat-related illnesses.

* Australia's wildfires have dwarfed other catastrophic blazes, with its burnt terrain more than twice the extent of that ravaged this year by fires in Brazil, California and Indonesia combined.

*Of nine fires in the state of South Australia, one was categorised as an emergency.

*Climate protests were also planned on Friday in cities such as Canberra, targeting the government's handling of the crisis and its position on climate change.

*Prime Minister Morrison said he was considering holding a wide-ranging national inquiry into the bushfires after the immediate crisis passed.

*Just shy of 2,000 homes have been destroyed in New South Wales, state authorities said, half during the past 10 days.

*The Commonwealth Bank of Australia is to donate cricketer Shane Warne's prized "baggy green" cap to a museum after paying more than A$1 million for it at an auction for bushfire relief.

*Authorities have warned that the huge fires, spurred by high temperatures, wind and a three-year drought, will persist until there is substantial rainfall. The weather agency said there was no sign of that for months.

*Ecologists at the University of Sydney have estimated 1 billion animals have been killed or injured in the bushfires, potentially destroying ecosystems.

* Mr Morrison has pledged A$2 billion ($1.4 billion) to a newly created National Bushfire Recovery Agency.

*About 100 firefighters from the United States and Canada are helping with another 140 expected in coming weeks.

*The fires have emitted 400 megatonnes of carbon dioxide and produced harmful pollutants, the European Union's Copernicus monitoring programme said.

*Smoke has drifted across the Pacific, affecting cities in South America, and may have reached the Antarctic, the U.N.'s World Meteorological Organization said.