A koala that was dramatically rescued from deadly bushfires in Australia has been put to sleep.

Footage of a woman carrying the injured animal from the raging fires on the New South Wales coast went viral on social media.

Toni Doherty used her shirt to protect the animal from the heat and smoke after rushing in to help.

He was taken to the nearby Port Macquarie Koala Hospital (PMKH) where he was treated for serious burns to his hands, arms, feet and legs.

Ms Doherty named him Ellenborough Lewis after one of her grandchildren - and over €1m has been donated to the hospital through a GoFundMe page in the days since the rescue grabbed international attention.

In a Facebook post this morning the hospital said it had taken the difficult decision to put Ellenborough Lewis to sleep.

It said his burns had worsened and his condition would not have improved over time.

“Today we made the decision to put Ellenborough Lewis to sleep,” it said.

“We recently posted that ‘burns injuries can get worse before they get better.’ In Ellenborough Lewis's case, the burns did get worse and unfortunately would not have gotten better.

“The Koala Hospital's number one goal is animal welfare, so it was on those grounds that this decision was made.”

The fires have already burned through millions of acres of farmland and bush in New South Wales in what is one of the most devastating starts to a fire season in history.

There were 125 bush fires burning across the state at 11pm local time – with 1,700 firefighters and 500 supporting crew continuing to fight them.

There have been a number of deaths and hundreds of homes have been destroyed. The state is also suffering some of the highest levels of air pollution on record.

Peter the Koala who was rescued from the Lake Innes Nature Reserve. Image: Port Macquarie Koala Hospital/Facebook

The fires have had a devastating impact on wildlife – and the koala which was already struggling before this year’s fire season took hold.

Earlier this year, the Australian Koala Foundation warned that the animals were “functionally extinct” – although this claim has been disputed by some scientists.

Their numbers are hard to track as they are highly nomadic and live in many different habitats; however, experts generally agree that they are in steep decline.

An injured koala receiving care at the Port Macquarie Koala Hospital. Image: Port Macquarie Koala Hospital/GoFundMe

The PMKH GoFundMe page had an original funding goal of AU$25,000 and it has now reached AU$1,712,720.

The hospital has pledged to use the extra money to extend a koala drinking station project across New South Wales and to establish a wild koala breeding program.

The programme would see large swathes of koala habitat protected from development to allow the animals the space and safety to breed.