The state government imposed a ban effective from Monday on logging across 176,000 hectares (435,000 acres) of forest on the north coast for a Great Koala National Park, hitting six timber mills and about 300 workers.

Without action, it warned that koalas in Australia's most populous state could die off by 2050.

Environmentalists say koala numbers in New South Wales have suffered a dramatic decline in recent decades due to deforestation, drought and bushfires.

"Koalas are at risk of extinction in the wild in NSW -- that's unthinkable. The Great Koala National Park is about turning that around," said New South Wales Premier Chris Minns.

"We've listened carefully and we're making sure workers, businesses and communities are supported every step of the way."

State officials contacted each affected mill, the government said in a statement, vowing to provide payments to cover workers' salaries and business costs while offering free access to training, financial, health and legal services.

The state government first announced the planned koala haven in 2023 but it only stopped logging in 8,400 hectares of forest. The plan was also criticised for not protecting trees immediately.

- Gliding marsupials -

The Great Koala National Park will provide a refuge to more than 12,000 koalas, 36,000 greater gliders -- nocturnal marsupials with a membrane that lets them glide -- and more than 100 other threatened species, officials said.

The government said it would invest Aus$6 million (US$4 million) to support new tourism and small business opportunities in the area.

It also boosted funding to create the park by Aus$60 million -- in addition to Aus$80 million announced in 2023.

"This park will ensure future generations will be able to see koalas, greater gliders and other threatened species in the wild for many years to come," said Gary Dunnett, chief executive of the state's National Parks Association.

"The permanent protection of this magnificent area will also safeguard critical water catchments for the people of the Coffs Coast, protect sacred Indigenous sites and open up huge economic opportunities for regional green tourism. It is truly a win-win for the people of NSW and nature."

When connected with existing national parks, the koala haven would create a 476,000-hectare reserve, the state government said.

Final creation of the koala park will depend on it being registered by the federal government as a carbon project for improved management of native forest, the state said. That assessment was underway.