BHP's Pilbara mishap.

BHP's Pilbara mishap. Photo: Supplied

RAIL services at BHP Billiton's highly lucrative iron ore operations in the Pilbara have resumed after a derailment on the group's main Newman line.

The derailment occurred on Saturday and BHP said any impact on the group's production would be shown in its June-quarter production report, due on July 20.

''No employees were injured or at risk and the relevant authorities have been notified,'' BHP said.

The group's iron division is investigating the cause of the derailment. No other details were provided but Pilbara sources said the damage bill could be as much as $20 million, given the damage to the locomotives.

BHP is the No.2 iron ore producer in the Pilbara behind Rio Tinto. Like Rio and third-ranked producer Fortescue Metals, BHP is spending up big to capitalise on the China-led boom in iron ore prices. In March, BHP's board approved $US7.4 billion in new capital investment.

The investment will lift BHP-owned and managed iron ore production in the Pilbara to more than 220 million tonnes a year.

Safety at its Pilbara iron ore operations has been a focus for BHP following a run of fatal accidents in 2008-09. At the time, BHP's iron ore president, Ian Ashby, said the five deaths in the West Australian operations were unacceptable. ''The reverberations of these events to business performance will be felt for some considerable time but, clearly, we won't relent until we've eliminated these sorts of incidents from our operations,'' he said.

Mr Ashby has since added that the deaths ''were partly due to a poor attitude to safety in the region''. ''There is a complacency generally in the Australian workforce and a bit of an arrogance. I think some of that is quite manifest in the Pilbara.''