A potentially lethal sexually-transmitted infection has been detected in the last disease-free koala population in one major city, heightening extinction fears for the endangered native marsupial.
Two koalas, part of a population in southwest Sydney already under threat from development, were found infected with chlamydia in September, the NSW environment department said in a statement on Friday.
The koalas returned a positive result for the disease following their rescue in the suburb of Appin after they were hit by cars.
Chlamydia, a highly contagious bacteria that causes infertility in koalas, has decimated their numbers in NSW, Queensland and the ACT, where they are listed as endangered.
In NSW, Labor made a 2023 pre-election pledge for a new national park in a bid to save the state's koalas, but the Minns government is yet to fulfil the promise, drawing criticism from the Greens and conservation groups.
Subsequent testing uncovered no further evidence of the disease in the southwest Sydney population, the department said.
Officials would "continue to monitor and expand testing in the coming months, using drones east of Appin to locate koalas and collect their scats for chlamydia testing", it said.
Greens MP Sue Higginson said it was extremely concerning chlamydia had entered one of the state's few disease-free koala populations as the park sanctuary continued to be delayed.
"I am devastated but not surprised about this tragic find in the koala population of southwest Sydney, this marks a horrid and significant further challenge for the ongoing survival of koalas in the wild in NSW," she said.
"It is clear that koalas in NSW are still on the path to extinction here," she added, claiming the government was failing on its "promise to do more to stop koalas edging any closer to extinction".
NSW Environment Minister Penny Sharpe was contacted for comment.
The proposed koala sanctuary, to be called the Great Koala National Park, could cover up to 176,000 hectares on the mid-north coast, according to the government.
Earlier in March, the government said it was still committed to establishing the park but had not yet determined its size.
In addition to chlamydia, the nation's koala population - estimated at up to 524,000 - is under threat from deforestation, introduced predators and climate change sparking increasingly severe bushfires.
