Many of Australia's biggest companies and local celebrities are coughing up tens of millions of dollars to provide assistance for volunteer firefighters, emergency services personnel and fire victims.

Key points: Acting CEO of the Australian Red Cross warns recovery can take years and funding support is required for the long term

Acting CEO of the Australian Red Cross warns recovery can take years and funding support is required for the long term Warning follows several public announcements by corporate donors in recent days

Warning follows several public announcements by corporate donors in recent days Andrew Forrest insists his family foundation's assistance is a long-term project

From mega-celebrities like Hollywood A-lister Chris Hemsworth, to corporate philanthropists like Andrew "Twiggy" Forrest, well known Australians and businesses have been falling over themselves to present hundreds of thousands, and in some cases tens of millions of dollars to the bushfire recovery effort.

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Mr Forrest, for example, announced on Thursday he will offer up $70 million through his Minderoo Foundation.

"This is a disaster and the Minderoo Foundation and my family will react to the scale of the disaster," he told PM.

He confirmed the contribution could rise, depending on what is needed to address the crisis, but he would not commit to lobbying the Morrison Government on climate change.

"I think we do what we can, I'm very fortunate to chair a large Australian public company," he said, referring to mining company Fortescue Metals Group.

"We're spending over $500 million to move away from diesel and oil, and of course coal, to solar and to gas.

"I think, as a company, leading by example is more important than preaching to people."

The National Australia Bank is putting $5 million towards the recovery effort, while Coles is donating $4 million and BHP $2 million.

'This is a marathon not a sprint'

However, charities on the front line of the bushfire recovery effort are pleading with corporate Australia not to go too hard out of the blocks with big cash donations.

The Red Cross welcomed the outpouring of donations but acting chief executive Noel Clement said few understand that ongoing funding is what is needed.

"We can continue to provide support for as long as the assistance is there quite frankly," he said.

"With the Black Saturday bushfires we were providing support for 10 years.

"There's still some support going out to some of those communities."

Disaster recovery experts believe the process of rebuilding communities affected by this season's bushfires could take more than three years and, as large as the donations are right now, they will not be anything like enough to fund recovery efforts a few years from now.

Andrew Forrest said the Minderoo Foundation was committed to contributing to the recovery long-term. ( AAP: Dean Lewins )

Mr Clement feared after this initial surge of financial support, the flow of money will turn into a trickle, especially as the bushfires fail to make the headlines.

"These are marathons, not sprints," he said.

"Now is the time people are wanting to give and that's fantastic and the support we get from others to promote the work we and others are doing in the field is terrific as well.

"As long as people realise that this is to support communities now and in the long term."

Mr Forrest insisted his commitment would be for the long-term and pointed to Minderoo's commitment to the Black Saturday fire recovery a decade ago.

"The Minderoo Foundation, which was nowhere near the scale and size and capacity it is now, stayed in that region for two years," he said.

"We played a very small part in their recovery."

Efforts to extend support

The country's peak corporate lobby group — the Business Council of Australia — has stepped up in this regard.

It has announced the creation of a trust to assist the families of volunteers killed while fighting fires, both during the current disaster and into the future.

And businesses, including ANZ, Qantas and Wesfarmers, are granting paid leave to workers who volunteer with emergency services.

PwC has gone one step further by uncapping the amount of paid leave on offer.

"We are a professional services firm and we have a lot of skills to be able to offer the community as well," PwC's chief people officer Dorothy Hisgrove said.

"We've already reached out to the federal and the state governments to offer, and we're waiting for them to say how best we partner and collaborate with them."

She said the consultancy's initial $500,000 donation will expand as the crisis develops.

"So I think over the longer-term our support for this will be not just in the immediate, but next year and the year after."

Of course, once disaster recovery organisations feel more confident about receiving ongoing funding, the next challenge is actually managing the money.

The bigger the donation, the more complex this process becomes.

"It's a really tough question when the fires are still going and people are yet to rebuild," the Red Cross's Noel Clement said.

"At the moment I couldn't tell you how much these communities need because the events are still happening and as far as I understand no-one's able to do a prospective assessment of: how far these fires could go and what could be the damage?

"It is tricky that we're raising money now; now is when people want to give and we don't know exactly how far-reaching the fires are going to be yet."