MELBOURNE – Western Australia approved BHP Group's application to disturb 40 culturally significant Aboriginal sites as part of a mine expansion, the state government said on Thursday, days after Rio Tinto blew up sacred rock caves in the same area.

State Aboriginal Affairs Minister Ben Wyatt said in a statement he had approved BHP's application to "impact" the sites in the iron ore-rich Pilbara region, where BHP is planning its $3.4-billion South Flank expansion.

Under a legal loophole, traditional owners are not able to object to ministerial decisions made under Section 18 of the state's Aboriginal Heritage Act when "land users conclude that impact to a site is unavoidable".

The loophole allows mining companies to apply for an exemption to damage or destroy cultural sites.

"No objections were filed and I approved the notice on 29 May, 2020. This notice covers 40 Aboriginal sites," Wyatt said in his statement.

BHP sent a statement to Reuters saying it would not disturb any sites without further study and consultation with the Banjima people to understand the cultural significance of the region where it has been active for more than half a century.

Chairperson of Banjima Native Title Aboriginal Corporation, Maitland Parker, said: "As a matter of lore and culture shared with other traditional owners across Australia and the world, the Banjima people do not support the destruction of sites of cultural significance." The approval came the same week Rio Tinto blew up two caves in the Juukan Gorge, one of which showed evidence of continual human habitation stretching over 46 000 years.

Wyatt said the area covered by BHP's application was subject to a 2015 land use agreement in which the Banjima people committed to support the South Flank project. That agreement included 72 exclusion zones containing sites regarded as significant by the Banjima People, he said.