Sydney - Australian koalas are dying by the thousands as a result of land clearing in the country's northeast, while millions of birds and reptiles are also perishing, conservation group World Wildlife Fund (WWF) said Sunday.

The environmental body warned that unless urgent action was taken to stop trees being felled, some species would be pushed to the brink of extinction.

In an annual statement, Queensland state last week revealed that 375,000 hectares of bush were cleared in 2005-06 -- a figure WWF said would have resulted in the deaths of two million mammals.

Among those that perished as a result of loss of habitat would have been 9,000 tree-hugging koalas, WWF Australia spokesman Nick Heath said.

"It's a horrifying figure," Heath told AFP. "Two million mammals and that's all sorts of kangaroos, wallabies. We couldn't come to an exact figure on the birds, but I would say it would be over five million."

Heath said WWF's figures were based on earlier scientific assessments of animal density in each area of the state combined with the amount of land cleared over the 2005-2006 period.

He said the animals that died in the largest numbers were reptiles, including lizards and turtles.

Of particular concern was the impact on the koala, an iconic marsupial found only in Australia and which is most populous in Queensland state.

"There is scientific debate about whether koalas are on the verge of extinction or not... I don't want to enter into that debate," Heath said.

"All I say is, whether they are endangered or not, killing 9,000 koalas is unacceptable.

"People want koalas to exist, they don't want them to be on the endangered list. And if we kill 9,000 a year, even if they are not on the endangered list now, they will be if we don't stop."

Heath said that turning native bush into grazing paddocks meant that many of the animals killed died in fires set by farmers to clear debris after bulldozers cut down the trees.

"So these animals die horrific deaths," he said. "They are either dead from being run over or falling from a tree, or if they survive that, they are burnt alive."

The Queensland government has set up a task force to help conserve koala populations amid greater urban development in the state's southeast.