An inquiry into the future of New South Wales' koala population has received hundreds of submissions amid claims extinction of the marsupial is "possible" without urgent action.

Key points: An NSW inquiry is looking into what needs to be done to protect koalas in the future

An NSW inquiry is looking into what needs to be done to protect koalas in the future The National Parks Association of NSW says without urgent action it is possible that koalas will become extinct

The National Parks Association of NSW says without urgent action it is possible that koalas will become extinct Metal-style fencing in residential areas has been raised as a major obstacle for koalas

The New South Wales parliamentary inquiry is looking into policies and government funding to ensure the longevity of healthy, sustainable koala populations and habitat in the state.

It will also focus on trends, key threats, resource availability, adequacy of protections and issues for further research.

The inquiry has received 259 submissions over the past three months and its final report is due in June next year.

Scientists, government officials, animal welfare groups and planners are expected to speak at its only hearing today in Sydney.

Evidence is expected to focus on the potential identification of key areas of koala habitat on private and public land that should be protected, including areas at risk of logging or clearing.

Other issues expected to be raised include climate change, the impact of bushfires and the environmental, social and economic impacts of establishing new protected areas — including national parks — to conserve koala habitat.

The state's koala population has declined by about 26 per cent in the past 15 to 20 years, according to the New South Wales Office of Environment and Heritage.

Last year the department developed the $45 million NSW Koala Strategy after it noted that, without significant intervention, the level of decline would be likely to continue.

Submissions to a NSW inquiry into koala protection call for design guidelines to protect the marsupial's habitat, which is under threat from housing developments.

A statewide inquiry is underway in NSW into the state's koala population. ( ABC News: Nic MacBean )

Extinction 'possible'

In its submission to the inquiry, the National Parks Association of NSW said the koala population was under enormous pressure.

"It is important for the committee to realise that the extinction of koalas in NSW is possible if we do not urgently change course," it said.

"The key threat to koalas is accelerating habitat loss from land clearing, logging and urban development," the association said.

"Many of the woodlands and forests upon which koalas depend have been identified as either 'crisis ecoregions' or 'very high risk ecoregions'."

The association recommended that the State Government proceed with the proposed Great Koala National Park.

It also called for a ban on logging and for koala habitat to be protected as a matter of urgency.

The NSW Government identifies areas where koalas are most at risk. ( Supplied: NSW Government )

Koalas bear the brunt of development

High-density housing projects and associated habitat loss have been identified as a major threat to koalas.

Submissions from environmentalists and planners have taken aim at housing developments springing up on land razed by bulldozers.

Campbelltown Council in Sydney told the inquiry that best practice guidelines for koala-sensitive design requirements were desperately needed.

Meanwhile EcoNetwork-Port Stephens, which operates in an area where a koala sanctuary and hospital are being built, blamed poorly planned housing development for the marsupial's demise.

"[There are] deaths from road traffic and dog attack, as well as threats to the viability of local koala populations from loss of suitable minimum scale areas of habitat," the company's Nigel Dique said.

"The status of koalas in Port Stephens has deteriorated to such an extent that koalas are now listed as vulnerable and the current population is eligible for listing as endangered."

High density housing estates across the country have reduced koala habitat. ( ABC News: Damien Larkins )

Unclimbable metal fences key koala threat

Metal sheet fencing, often referred to as Colourbond fencing, has also been identified as a major obstacle for koalas that hindered their ability to find food and companions.

Residents are urged to put wooden poles against their metal panel fences so koalas can climb them. ( Supplied: QLD Government )

Koalas are known to wander across open areas including backyards, lawns, sporting fields, roads and footpaths, but koala rescue groups told the inquiry that that style of fencing was a deterrent to the animal's natural movement.

In its submission, the Queensland Department of Environment and Science urged homeowners in koala habitats to make their fences climbable and use timber posts and rail, chain wire or slats with at least a 1cm gap between each slat.

Residents were urged to place wooden poles at least 10cm wide at a 45-degree angle to the base of their metal fence to allow a koala to climb up.

In the community of Lemon Tree Passage near Newcastle, many wooden fences have been replaced.

In outlining its concerns to the inquiry, the Lemon Tree Passage Parks, Reserves and Landcare Group explained its first-hand account of the detrimental impact of metal-style fences.

"Many of the fences in Lemon Tree Passage have been changed from timber to the Colorbond type that koalas cannot climb.