Firefighters drag their water hose after putting out a spot fire near Moruya, Australia, Jan 4, 2020. (RICK RYCROFT / AP)

SYDNEY/MELBOURNE - Bushfires burned dangerously out of control on Australia's east coast on Saturday, fuelled by soaring temperatures and strong winds that had firefighters battling to save lives and property, and authorities said the worst of conditions was yet to come.

By late evening, Victoria had 14 fires rated at emergency or evacuate warning levels, and New South Wales had 11 rated emergency, with more than 150 others burning across the states. New fires had started, and others had broken containment lines.

The bushfires are generating so much heat that they are creating their own weather systems including dry lightning storms and fire tornadoes

"There are a number of fires that are coming together - very strong, very large, intense fires that are creating some of these fire-generated thunderstorms," New South Wales Rural Fire Service (RFS) Commissioner Shane Fitzsimmons said at an evening briefing.

"And unfortunately we've still got many hours to go of these elevated and dangerous conditions."

As the RFS updated its emergency warnings on the fires, it repeatedly delivered the same blunt advice to those who had not evacuated at-risk areas: "It is too late to leave. Seek shelter as the fire approaches."

The Bureau of Meteorology (BOM) said conditions were deteriorating rapidly as a gusty southerly change pushed up the coast and smoke plumes from the fires triggered storms.

The bushfires are generating so much heat that they are creating their own weather systems including dry lightning storms and fire tornadoes.

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The weather conditions are the results of the formation of pyrocumulonimbus clouds, which are essentially a thunderstorm that forms from the smoke plume of a fire as intense heat from the fire causes air to rise rapidly, drawing in cooler air, according to information from the Australian Bureau of Meteorology.

As the cloud climbs and then cools in the low temperatures of the upper atmosphere, the collisions of ice particles in the higher parts of the cloud build up an electrical charge, which can be released as lightning.

The rising air also spurs intense updrafts that suck in so much air that strong winds develop, causing a fire to burn hotter and spread further.

This Jan 3, 2020 AFP graphic shows the location of areas affected by fires since September 2019 in Australia.

Authorities have said conditions could be worse than New Year's Eve on Tuesday, when fires burnt massive tracts of bushland and forced thousands of residents and summer holidaymakers to seek refuge on beaches.

In Victoria, Premier Daniel Andrews said while conditions were difficult, the job of firefighters had been made easier by tens of thousands of people following advice to evacuate.

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It may be Sunday or later before damage assessments can be made. Prime Minister Scott Morrison put the national death toll from the current fire season, which began in September, at 23. Twelve of those are from this week's fires alone.

The federal government said that up to 3,000 army reservists would be deployed to help communities hit by spreading wildfires and a third navy ship had been readied to support evacuations from coastal towns.

The government announced an unprecedented call up of army reservists to support firefighters as well other resources, including a third navy ship equipped for disaster and humanitarian relief

It is the first time there has been a compulsory call out of reserve brigades in Australia, underlining the scale of the emergency. They will help deliver supplies to isolated communities, evacuate people in need, and assist in reopening roads and preparing fire breaks to contain the blazes.

Managing bushfires is the responsibility of state governments and fire services, but the unprecedented scale of the fire season demanded a national response, Morrison said. 

In South Australia, two people died on Kangaroo Island, a popular holiday spot not far off the coast, taking the national toll from this week's fires to 12. Twenty-one people remain unaccounted for in Victoria, down from 28 reported on Friday.

Andy Gillham, the incident controller in the Victorian town of Bairnsdale, said the area had avoided the worst of the fires on Saturday but stressed this was an exceptional fire season.

Residents used social media to post photos of the sky turning black and red from the smoke and glare of the fires, including in the Victorian town of Mallacoota, where around 1,000 people were evacuated by sea on Friday.

The first of those evacuees arrived near Melbourne on Saturday morning after a 20-hour journey by boat and a second ship with about 1,000 people landed in the afternoon.

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Morrison said he has cancelled official trips to India and Japan that were scheduled for the second half of January so he could tackle the country's growing fire crisis.

"I should stress that both of those scheduled meetings are postponed and will move quickly to identify another opportunity," Morrison told reporters.

Morrison had been set to leave for India on Jan 12, followed by a trip to Japan, with talks due to focus defense, intelligence and security and trade issues.

The decision to postpone the trips came after Morrison faced heavy criticism in December for taking off on a family holiday to Hawaii while fires raging across Australia since September continued to burn. He cut the family trip short and apologized.