University of Newcastle researchers Dr Ryan Witt and Associate Professor John Clulow were commissioned by a local action group to assess the impact of the Brandy Hill Quarry expansion in Port Macquarie on the local koala population.

The pair concluded in their report that the expansion, already approved at the state level, would sever a koala corridor, disrupt breeding processes and destroy prime koala habitat critical to the species' survival.

In the 24-page report, they urge federal Environment Minister Sussan Ley to consider the impact on the population in the context of declining koala numbers in NSW, exacerbated by last summer's bushfires.

The project on the NSW north coast, which was approved by the NSW Independent Planning Commission in July, would see 52 hectares of koala habitat cleared.

When handing down the decision, the commission said a review of koala impact policy framework may be required.

"The commission is of the view that in light of the 'Black Summer' bushfires and the parliamentary review (into koala habitat), it may be appropriate to re-evaluate the policy framework under which the impact on koalas is required to be assessed," their report says.

NSW Labor environment spokesperson Kate Washington said the expert report and the commission's comments exposed the weakness of the state's koala protection laws.

"It's inconceivable that this project could be approved on the back of the Black Summer bushfires and in the wake of the recent parliamentary inquiry into koala habitat," she said in a statement on Thursday.

"Bulldozing 52 hectares of core koala habitat in an area where there are healthy, breeding koalas is contrary to every recommendation of the inquiry."

"This is how koalas become extinct."

Ms Ley will now assess the project against the Commonwealth's Environment Protection and Biodiversity Conservation Act, and is expected to make a decision on September 8.

Australian Associated Press