Bushfire experts warn expanding suburbs in Canberra's west will leave new homes 'in the line of fire'

Bushfire experts have raised concerns about moves to build new suburbs to the west of Canberra – saying homes built there would be directly in the "line of fire".

The ACT government has begun an assessment of a 10,000 hectare swathe of land for future city expansion, known as the Western Edge Investigation Area.

The 20-kilometre stretch of mostly rural land runs from the existing suburbs of Belconnen south to Tuggeranong, and west to the Murrumbidgee River.

But in grim echoes of the 2003 Canberra firestorm that claimed four lives and some 500 homes, fire scientists say the city will face even greater bushfire threats from the west in the future.

They also say those suburbs would be hardest hit by fires.

They've warned the government that deadly fires are likely to become more frequent, and planners shouldn't put land sales revenue above community safety.

Growing capital expands westward

With Canberra's population set to nearly double within the next 40 years the hunt is on for new supplies of suitable suburban land.

The government has a policy of building 70 per cent of new homes within Canberra's "existing footprint", but even a modest 30 per cent suburban expansion would require tens-of-thousands of new homes in greenfield estates.

The government had previously ruled out developing land at Kowen, east of Canberra, effectively leaving the city only one direction – west – in which to expand.

But it's long been a controversial proposal – with the former Land Development Agency criticised by the ACT Auditor General for a "lack of probity" over its $43 million purchase of rural land in the west.

ACT Environment, Planning and Sustainable Development Directorate (EPSDD) deputy director Erin Brady said it would now take around a decade to complete its exhaustive studies.

"Land is not infinite in terms of land that's available for investigation, so this really is one of the big areas for us to look at to see if there is capacity," Dr Brady said.

"It's to be investigated for what are the best future uses, so that could be (environmental) offsets, rural uses ... or whether there is capacity to have residential development out there."

Suburbs in the 'line of fire'

But a panel of government-appointed independent experts has sounded alarm bells, saying it has "very serious concerns about the quality" of the government's bushfire risk assessment of the area.

The ACT Bushfire Council pointed to glaring mistakes in the government's initial technical studies, claiming consultants misread the topography and bush cover.