Habitat loss, urban expansion, vehicle collisions and disease have made koalas in Queensland, New South Wales and the Australian Capital Territory "vulnerable," Environment Minister Tony Burke said.
The numbers have fallen by as much as 40 percent since 1990 Ii New South Wales and Queensland, Burke said, and the decision to list the koala "follows a rigorous scientific assessment."
"We're talking about a species that is not only iconic in Australia, but is known worldwide, a species that has taken a massive hit over the last 20 years and we can't wait any longer before we turn the corner when the scientists are telling us the evidence is in," he said.
The listing does not cover all areas of the country, as population numbers for koalas are holding in the states of Victoria and South Australia.
Some conservationists, such as Deborah Tabart from the non-profit Australian Koala Foundation, said the listing of koalas as threatened should have been national, the BBC reported Monday.
"The koala is such an important tourist icon and such an important symbol to Australia," she said.