People were warned on Wednesday to prepare for another wave of evacuations as temperatures in the southeastern part of Australia began to rise after a days-long cool spell, bringing the danger of revitalized blazes.

Firefighters have used the break from extreme heat and high winds to strengthen containment lines around several major fires, as the military continued efforts to provide supplies to thousands of people who have been left homeless.

Complicating the recovery effort, authorities have forecast another temperature spike as soon as Friday, with little rain, meaning a return to hazardous conditions.

"We are going to see some widespread severe fire danger, we are asking people to be ready," Shane Fitzsimmons, New South Wales (NSW) state Rural Fire Services Commissioner, was quoted by Sky News as saying.

More than 10.3 million hectares (25.5 million acres) of land – a land size equivalent to South Korea – has been razed by bushfires that have killed 24 people in recent weeks.

On Wednesday, ecologists at the University of Sydney doubled their estimate of the number of animals killed or injured in the fires to one billion, as the UN World Meteorological Organization confirmed that smoke from the blazes has drifted as far as South America.

The three major cities in Australia's southeast, Sydney, Melbourne and the capital Canberra, were all blanketed in thick smoke, putting them among the most polluted cities in the world.

Officials were working to restore telecommunications and power to thousands of people in rural areas, and warned that enforced blackouts may be necessary if systems become overloaded.

The bushfire crisis follows a three-year drought that has left much of the country's bushland tinder-dry and vulnerable to fires.

Besides the extreme heat and dry conditions, dozens of people are directly to blame for some of the fires.

Police in New South Wales (NSW) were reported to charge at least 24 people for intentionally starting the fires in the state, which suffered seriously in the months-long bushfires.

It's reported that since November 8, NSW Police have taken legal action against 183 people, 40 of whom are juveniles, for fire-related offenses. 

(With input from Reuters)