Rio Tinto says Australia’s biggest aluminium smelter at Tomago will be unviable beyond 2028 based on the power price contracts offered to date, and the mining giant wants to decide on the smelter’s future within six months.

Speaking just hours after Glencore chief Gary Nagle said high power prices were threatening the future of Queensland’s only copper smelter, Rio chief Jakob Stausholm said efforts to strike a clean energy future for the Tomago smelter in NSW were lagging the strong progress made for Queensland’s Boyne smelter.