BHP has accused the law firm behind a £36 billion ($68 billion) class action relating to the 2015 Mariana dam disaster in Brazil of lacking candour about the number of people it claims to represent in the bitter dispute.

The class action was filed by London law firm Pogust Goodhead in 2018 on behalf of 200,000 claimants affected by the collapse of the Fundão tailings dam at the Germano iron ore mine in Brazil.