Just weeks after Australia's worst bushfire season killed an estimated 8,000 koalas, authorities are investigating reports that dozens more have been wiped out by loggers.

A registered nurse claims at least a dozen koalas are dead and another 60 seriously injured after a bluegum plantation in Portland, Victoria, was bulldozed.

Helen Oakley surveyed a small area of the property, which she said 'smelt like death', and said she'd already seen dozens of dead and injured koalas.

In a tearful video explaining the devastation, Ms Oakley said the logging company 'bulldozed 140 acres now and have just killed all of our koalas.'

Ms Oakley witnessed dozens of dead koalas when she was scouring the bulldozed land

'There are koalas lying there dead,' she said. 'Mothers killed with their little babies.'

Ms Oakley said the government was responsible for stepping in and doing something about the issue, but insisted 'nobody has done anything.'

'Australia should be ashamed of this... We need help.'

Local MP for the region Andy Meddick also spoke of his devastation after pictures o the dead koalas emerged overnight.

He said he would do all that he could within his electorate to get to the bottom of the situation and save the animals.

Other koalas which survived the initial impact were eventually euthanised due to their injuries

Ms Oakley found one koala with a broken arm which later had to be euthanised despite best efforts to save him

'As bushfires ravage parts of our state, killing millions of native animals, a bluegum plantation full of koalas is being cleared in my electorate of Western Victoria,' he said.

'According to local sources, hundreds of koalas have been impacted. Some have been killed, many injured.'

Mr Meddick said a law was passed in January 2017 making it mandatory in the state for individuals or businesses to report koala deaths.

He promised to raise that issue as soon as he could.

'I know how distressing this is, and thank you to all who have raised it with me. I promise I'll do all I can.'

Wildlife experts estimate at least 8,000 koalas have perished in Australia's deadly bushfire season, which is almost a third of the entire population in New South Wales

The Department of Environment, Land, Water and Planning are investigating the incident.

Ms Oakley told Yahoo News some of the surviving koalas were so badly injured medics were forced to euthanise them after rescuing them.

'The surviving koalas are being brought down from trees and the vets are checking them for hydration and malnutrition as they're all covered in ticks... a lot of them had to be euthanised'

She said one of the koalas which was later put to sleep was discovered with a broken arm.

A registered nurse claims at least a dozen koalas are dead and another 60 seriously injured after a bluegum plantation in Portland, Victoria, was bulldozed (pictured)

'I've never seen so many koalas in a concentrated area like this and so much death and smell.

'I started thinking if these were humans what this would be like and I just lost it.'

Wildlife experts estimate at least 8,000 koalas have perished in Australia's deadly bushfire season, which is almost a third of the entire population in New South Wales.

Ecologists say the animals may disappear from some regions and have to be reclassified as an endangered species.