Rio Tinto's explanation for how it came to destroy a culturally significant site in Western Australia has ''served to deepen the anguish'' felt by the traditional owners.

Rio conceded last week it had failed to grasp the significance of the 46,000-year-old heritage site within Juukan Gorge and had communicated poorly with the Puutu Kunti Kurrama and Pinikura (PKKP) people about the schedule for developing their ancestral lands.