Rio Tinto has agreed to pay almost $140mn to settle a long-running class action lawsuit that had accused the world’s second-largest mining company of concealing issues in the expansion of its Oyu Tolgoi copper mine in Mongolia. 

According to a proposed settlement filed in the US on Wednesday, the Anglo-Australian company will pay $138.75mn to end the case, which was brought by US hedge fund Pentwater Capital on behalf of minority investors in Turquoise Hill Resources, a Canadian company that was majority owned by Rio at the time the allegations were made. 

The lawsuit was originally filed in 2021 after Pentwater claimed senior executives at Rio and Turquoise Hill had known the $6.75bn expansion of the Oyu Tolgoi copper mine would run significantly over time and budget months before the problems were disclosed to investors. Rio and Turquoise Hill had said the complaint was “without merit”.