Disturbing numbers of koalas are being killed and injured by loggers in timber plantations across south-east Australia.

Thousands of koalas have taken refuge in the vast timber plantations that have emerged across the region, which are increasingly maturing for harvest.

But koala experts and wildlife refuge staff say many koalas are being wiped out during the logging process.

The ABC's 7.30 program has been provided with damning evidence of the carnage, the scale of which has previously been kept confidential.

"It's happening in our country," said Dr Stephen Phillips, a member of the Federal Government's Koala Abundance Working Group.

"We create a big brouhaha when we see it happening to cattle in a slaughterhouse in Indonesia or somewhere like that, but this is happening in our own backyard with a much bigger impact.

"This is a national and international icon that we are treating with so much disrespect and disdain."

It was workers with logging and timber companies, worried by what they had witnessed, who first blew the whistle about the koala deaths and injuries.

They did so anonymously, for fear of losing their jobs.

"It was a daily thing, sometimes a couple every hour, sometimes just one a day," one worker told 7.30.

"You normally come across them on the ground already dead or pretty badly injured."

Tracy Wilson, a wildlife rescue volunteer from Koroit in Victoria, says she deals with koalas with horrendous injuries.

"Broken limbs, impact wounds, broken backs, severed arm, dead mothers with joeys still alive trying to survive," she said.

"I had one 500 gram joey... that had two healed broken arms, so we can only assume from that the mother had been dropped previous to this incident.

"She had no obvious breaks but her intestines were just pulp."

'We're facing a crisis'

Wildlife rescuer Jill Rowley from Mt Gambier in South Australia says sometimes a logging company calls to get help for injured animals.

"I am aware that in that particular location there was 21 koalas killed. Fourteen of those I personally had to euthanise," she said.

"From another plantation we got 28 out and some of them were dead and some alive.

"There was an original estimate from one of the workers there, there were over 50 in that plantation. We're not sure what's happened to them."

Wildlife volunteer Shannon McKay from Warrnambool says she has been dealing with a similar influx.

She is currently treating three koalas.

"I think about 20 koalas came in from this particular plantation and it was a fairly small one," she said.

"So looking at the hectares of plantation in western Victoria and across into South Australia, I think we're facing a crisis with these guys."

Government vows to find solution

No-one from industry would be interviewed for the 7.30 program, leaving that to the Victorian Department of Environment and Primary Industry's Andrew Pritchard.

"We provide the overarching guidelines about how animals like koalas are supposed to be handled," he said.

When 7.30 asked if the the department did checks he replied: "We haven't previously."

"We take information reported through to us and work with industry as we are at the moment," he added.

"We're certainly working with industry for them to be able to achieve a better outcome that certainly what has happened in the past."

Ms Wilson remains sceptical that the department's preference for industry self-regulation will work.

"It sure hasn't happened to date. Obviously an industry doesn't want to be exposed for doing the wrong thing, I think some people have been doing it for so long they get numb to it," she said.

Dr Phillips agreed, adding: "That doesn't mean we can abrogate our responsibilities to act ethically in taking care in particular of species like the koala that has moved in and colonised those plantation areas."

"It's probably one of the most iconic mammals in the world next to the panda," he said.

Mr Pritchard insists a solution will be found, but agrees much work remains to be done.

When asked if his department has done an estimate of how many koalas may be involved, he replied: "It's something we're working with the industry on to try and determine how big this problem is."