Indigenous leaders have filed an unprecedented compensation claim against the West Australian Government that could become one of the world's biggest legal payouts.

Key points: Noongar People are pursuing more than $290 billion from the WA Government

Noongar People are pursuing more than $290 billion from the WA Government The compensation is for "spiritual damage" caused by loss of traditional land

The compensation is for "spiritual damage" caused by loss of traditional land The group's native title claim covers an area almost as big as Victoria

Noongar people of south-west WA are pursuing more than $290 billion for "spiritual damage" caused by loss of their traditional land.

The figure would be almost a quarter of Australia's gross domestic product of $1.4 trillion and more than West Australia's gross state product of $259 billion.

If the action is successful, it would put it in the range of a landmark $US206 billion ($304 billion) payout made by the tobacco industry to governments across the United States in 1998.

Noongar woman Naomi Smith, a lead claimant, said her people had been struggling since European settlement when they lost access to their traditional land.

Lead claimant Naomi Smith with lawyer David Stevenson. ( ABC News: Robert Koenig-Luck )

She said this claim was seeking reimbursement for the extinguishment of their native title rights over vast swathes of their country.

"It's going to be huge in regard to what Noongar people could do for our Noongar kids," she said.

David Stevenson, the solicitor representing Ms Smith, said it was "far and away" the largest claim made in Australia.

"It's effectively the largest litigation and largest compensation claim in the world," he said.

Since 2003, the traditional owners have claimed native title over 19.7 million hectares of land, an area almost the size of Victoria.

A map showing the Noongar People's compensation claim area, which is about the size of Victoria. ( ABC News )

But their rights to the vast majority of this land, 19.4 million hectares, have been "extinguished" because it was now used as government land, or for commercial, residential, agricultural or mining purposes.

This extinguishment meant the Noongar people were no longer able to exercise their traditional rights on the country.

"This is about our cultural and spiritual damage, as all the damage to our land," Ms Smith said.

Lead claimant Naomi Smith says "it's going to be huge" in regard to what Noongar people could do for their children. ( ABC News: Robert Koenig-Luck )

"The Noongar people were fed up … hopefully our people will get something out of this."

Lawyers confident of success

The claim was filed in the Federal Court last week and was yet to be heard by a judge.

Lawyers representing the group said they were confident the claim would be successful, as their case was based on a precedent set earlier this year in a native title compensation test case.

The High Court awarded $2.5 million in compensation to traditional owners of Timber Creek in the Northern Territory for 170 hectares of land that had native title extinguished.

They were awarded $15,000 in compensation per hectare, for economic and emotional damages.

Lead claimant Naomi Smith and lawyer David Stevenson met with elders Friday morning. ( ABC News: Robert Koenig-Luck )

Lawyers in the Noongar claim were using the same formula, pursuing $15,000 per hectare for the 19.4 million hectares of extinguished native title on Noongar country.

"$300 billion might sound unreasonable but this is for an area the size of Victoria," Mr Stevenson said.

"This isn't something we plucked out of the air, we have been working on it behind the scenes for months, we've been working with experts to get this figure."

He said the final compensation figure could even exceed his own expectations.

"We may have been a little too conservative, it could have been a little bit larger," he said.

"It's not whether the state can afford it, it's simply that what is owed."

One potential catch

But there was a potential sticking point in the case — compensation can only be paid for the native title areas extinguished after the 1975 Racial Discrimination Act was brought into effect.

Mr Stevenson said it was unclear what portion of the land fell into this category, but a team of experts were working to calculate the final figure.

One of the lead solicitors on the Mabo case, Greg McIntyre SC, who is also the president of the Western Australian Law Society, said this factor could greatly reduce the amount of land eligible for compensation.

"I think there are some difficulties about [the Noongar people] being successful in a claim of that kind," he said.

"Lots of the extinguishing of native title for Noongars and in Western Australia generally pre-date the 1975 Racial Discrimination Act.

"It may [however] attract a negotiated result [between the Government and Noongar people]."

Greg McIntyre said there may be some hurdles for the claim to overcome. ( ABC News: Robert Koenig-Luck )

The State Government had earlier agreed to a $1.3 billion native title settlement with the South West Aboriginal Land and Sea Council, on behalf of the Noongar people, but it is yet to be finalised.

This agreement had initially stalled in the courts when some Noongar elders refused to sign the deal.

The deal, which would see up to 320,000 hectares of Crown land handed over to the Noongar Land Estate, was registered by the National Native Title Tribunal last year, but is currently subject to appeal.

Now the same leaders who refused to sign the deal, including Ms Smith, are leading the charge for this new claim.

She said she felt there was solidarity behind this push, but they would continue to consult with all Noongar people.

"They are fully supporting it, they are supporting it all the way, so it's going to be huge for the Noongar people."

Premier says claim 'way over the top'

WA Premier Mark McGowan said his Government would fight the claim.

"A $290 billion claim is pretty extreme," he said.

"We will get advice on what the best course is but it sounds way over the top to me."

Mr McGowan said the State Government had already reached a deal under the Indigenous Land Use Agreement with the Noongar nation.

"The Noongar settlement has already occurred," he said.

"I don't know the details of it but clearly we've already reached a settlement with the Noongar people."

The South West Aboriginal Land and Sea Council will continue to pursue the Indigenous Land Use Agreements with the State Government, and did not put forward or endorse the compensation claim.

Editor’s note: An earlier version of this story incorrectly stated the Noongar people were granted Native Title in 2008. It was also updated on December 16, 2019 to include more information on the Indigenous Land Use Agreements between the State Government and the South West Aboriginal Land and Sea Council.