A worker was fatally injured at the Worsley alumina refinery on September 29.
BHP Billiton this morning confirmed that an employee working at the Western Australian refinery was fatally injured in an incident in the powerhouse.
It is understood the man was working in an elevator when he fell down the shaft.
A statement from BHP said the company extended its deepest condolences and support to family, friends and colleagues at this difficult time.
A spokesperson for BHP said the relevant government bodies are involved in a full investigation now underway, including the Department of Mines and Petroleum, Western Australian Police and Worksafe.
The identity of the worker has not yet been released.
The powerhouse at Worsley alumina refinery provides steam, power and air to the refinery, and includes a coal fired boiler/turbine cogeneration plant and gas turbine/waste heat boiler cogeneration plant.