Global miner BHP Billiton has flagged potential job losses at some of its Australian operations as it reins in costs amid falling commodity prices.

Speculation is mounting that jobs could be cut at some of the BHP's joint venture coal mines in Queensland's Bowen Basin and at its Brisbane office as the company faces a slowdown in industrial activity in China.

BHP, which is in a blackout period prior to reporting its full year results next Wednesday, is unable to say whether job losses would occur in Queensland or WA.

"Against a backdrop of increasing costs and falling commodity prices, we continue to focus on reducing our overheads and operating costs across the business," BHP said in a statement today.

"We don't intend to provide any detail about specific adjustments, but clearly there may be some impact on jobs in some areas."

The statement comes against a backdrop of a slowdown in China's economy, economic turmoil in Europe and some economists predicting the end of the mining boom in two years.

BHP recently denied reports that it had decided to delay its $30 billion Olympic Dam mine and $19 billion Port Hedland harbour expansions for at least two years.

The world's biggest resources company is expected to post a fall in operating profit from an Australian record $US23.6 billion last year to about $US16.9 billion in 2011-12, but it may have to write down some shale gas assets.