BHP says it is currently working flat out to mine for minerals

Strong global demand for commodities such as copper, zinc and iron is creating new opportunities for mining firms such as BHP.

But "a shortage of people, equipment and supplies", tight labour markets, and difficulties in sourcing machinery have increased costs, the firm said.

A weaker US dollar is also making it more costly to purchase equipment.

BHP's comments came is it unveiled its latest production report, showing a big jump in copper output and a 2% rise aluminium production on a year ago. However, iron ore and nickel production was hit by bad weather.

'Make hay'

The problems of rising costs have been cushioned by the big prices being commanded by raw materials.

Nickel, used to make stainless steel shine, sold for an all-time high of $20,000 a tonne in the latest London Metal Exchange floor session.

And copper, which is used in construction and electrical wiring, has recently climbed to record highs, jumping almost 6% to $7,230 a tonne, while zinc hit a record of $3,385 a tonne.

"Prices have been rarely, if ever, this high," Australia & New Zealand Bank commodities analyst Andrew Harrington said. "Now is the time to make hay."

Analysts expect BHP Billiton to meet market forecasts for a full-year profit of about $9.8bn.

BHP, which recently announced a $2bn share buyback, is listed on a number of international exchanges, including Sydney and London.