Plans announced on Tuesday by Rio Tinto, the Anglo­Australian mining group, to build its largest aluminium smelter in Malaysia’s Sarawak state could rescue the fortunes of the Bakun dam, which has been criticised by environmentalists as a “white elephant” that threatened Borneo’s habitat and indigenous people.

The Bakun dam, which would power the Rio Tinto smelter, was one of several mega-projects launched in the 1990s by Mahathir Mohamad, the former Malaysian prime minister, but was plagued by delays.