By David Winning

SYDNEY--Two ancient rock shelters in northwestern Australia's minerals-rich Pilbara region contained a trove of artifacts, indicating they had been occupied by humans more than 46,000 years ago.

Last month, Rio Tinto PLC blew the caves up.

The chain of events that led to the caves at Juukan Gorge being destroyed on May 24 is now the focus of an investigation by Australian lawmakers, including whether laws that allow mining companies to dig up minerals on land with indigenous heritage sites are still fit for purpose.

Rio Tinto has apologized for the destruction of the caves and acknowledged that its actions had damaged trust between the company and the traditional owners of land around the Juukan Gorge site, the Puutu Kunti Kurrama and Pinikura people, or PKKP.

On Friday, Rio Tinto said it would review how it approaches heritage issues. The company also said it would cooperate with a federal parliamentary inquiry by the Northern Australia Committee, which will look at decisions taken by Rio Tinto that led to the caves being destroyed, among other issues.

Around the world, resources companies dig up metals and minerals in areas that require them to work closely with local communities. Many of their operations are on land traditionally owned by indigenous groups, including in South America, Africa and the Arctic Circle. However, their activities can be a source of friction if residents don't feel they benefit from the mining activity nearby.

Tensions were recently sharpened by the coronavirus pandemic, with mining companies overhauling the way they work to protect vulnerable indigenous people who live close by, including shuttering several operations temporarily. Still, some miners were hit by protests, illustrating the mistrust that often lies below the surface locally.

About 60% of the world's iron ore traded by sea comes from the Pilbara, including from Rio Tinto's operations, and the region is a major source of the commodity for China and other fast-growing economies.

Rio Tinto has been working closely with the PKKP in regard to the Juukan area since 2003, and formally reached an agreement for use of the land in 2011.

The miner didn't break any laws when laying explosives at Juukan Gorge. It was authorized by the Western Australia state government to conduct activity at its Brockman 4 mine that would impact the rock shelters.

However, the PKKP said archaeological research at the site since 2013, when Rio Tinto was granted authorization, had revealed several ancient artifacts, including a bone fragment sharpened into a pointed tool, grinding and pounding stones, and plaited human hair that appeared to have come from an ancient hair belt.

The PKKP said it was first advised of Rio Tinto's intention to blast the gorge near the rock shelters on May 15, and that explosives had been laid. Attempts to negotiate with Rio Tinto to stop the blast foundered when independent experts advised it wasn't safe to remove the charges, the indigenous group said.

"We recognize that Rio Tinto has complied with its legal obligations," John Ashburton, chairman of the Puutu Kunti Kurrama Land Committee, said the day after the caves were blasted. "But we are gravely concerned at the inflexibility of the regulatory system which does not recognize the importance of such significant archaeological discoveries within the Juukan Gorge once the minister has given consent."

Rio Tinto said Friday it was determined to learn lessons from what happened and supported reforming laws governing Aboriginal heritage. As part of its review led by nonexecutive director Michael L'Estrange, Rio Tinto said it would seek input from the PKKP.

"Our immediate priority is to regain the trust of traditional owners, starting with the Puutu Kunti Kurrama and Pinikura people," said Rio Tinto Chief Executive Jean-Sébastien Jacques. "We very much look forward to incorporating the findings of the board-led review into our heritage processes and approach."

A final report from Rio Tinto's internal review is due in October, about a month after the Northern Australia Committee aims to publish conclusions from its own investigation.

Write to David Winning at david.winning@wsj.com