BHP Billiton, the world's biggest mining company, is studying the next step in simplifying its portfolio to focus on iron ore, copper, coal and petroleum, after a two-year campaign of global asset sales.

Options include spinning off its aluminum, nickel and bauxite assets in a Aus$20 billion deal, the Australian Financial Review reported today.

The simplification is a priority, the company said yesterday in a statement, without directly commenting on a possible spin-off.

BHP and Rio Tinto have been leading a global push for asset disposals as mining groups focus on their most profitable operations after a 10-year boom in metal prices waned.

BHP confirmed in March 2013 it was planning to sell about 10 assets, as $48 billion of mines and businesses hit the global market. – (Bloomberg)