Global mining titans BHP and Rio Tinto have backed a high-profile campaign to give indigenous Australians a constitutionally guaranteed voice in white-dominated politics, saying Prime Minister Scott Morrison's opposition to the proposal did not "stand up to scrutiny".

On Thursday, BHP Group and Rio Tinto issued a statement in support of a constitutionally enshrined body to advise parliament on indigenous matters.

"A first nations voice to parliament is a meaningful step towards reconciliation," BHP Chief Executive Officer Andrew Mackenzie said.

"It would empower indigenous Australians. It would make sure indigenous people have a say on the legislation, policy and programmes that shape indigenous lives, families and communities."

Out of 150, only five members of the Australian parliament are Aboriginal.

The opposition Australian Labor Party has promised a referendum on the issue if it wins power in the May election.

'Nothing to fear'

Australia has struggled for decades to reconcile with descendants of first inhabitants, who arrived on the continent some 50,000 years before British colonists.

The constitution makes no reference to indigenous people, whose leaders have struggled for generations to gain recognition for past injustices since European colonisation in the 1700s.

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The government only issued a formal apology to indigenous people in 2008.

Late last year, Morrison's conservative government rejected a proposed advisory body comprised of elected indigenous Australians, saying it would create a de facto third chamber in parliament.

"These fears don't stand up to scrutiny," Mackenzie said, referring to a 2017 report by indigenous leaders that recommended the advisory body.

"The final report ... found that there was nothing to fear from giving indigenous Australians the constitutionally enshrined voice they deserve," he said.

'A bright future'

Corporate support for the plan comes after decades of controversy between mining, oil and gas companies, which form the backbone of the Australian economy, and Aboriginal landowners.

There have been frequent disputes between Australia's largest firms and traditional landowners over compensation, damage to sacred sites and titling. Many cases end up in court.

Australia's 700,000 or so indigenous people track near the bottom of its 25 million citizens in almost every economic and social indicator.

During a visit to Brisbane on Thursday, Morrison said he disagreed with the mining companies.

"I want to see indigenous families in jobs. I want to see indigenous kids safe and I want to see them in school because that's what gives them a bright future," he said.

Karen Mundine, CEO of the non-profit group Reconciliation Australia and citizen of the Bundjalung Nation, told the Sydney Herald that her organisation strongly welcomed the move by Rio Tinto and BHP.

"I'd like to encourage other corporate organisations to do the same," she said. "Millions of Australians work in corporate organisations, which are embedded in communities around the country. How corporate organisations relate to and engage with these communities helps shape who we are."