A Mount Arthur employee received the threat by phone, prompting management to instruct workers to tip loads and assemble to nearby emergency points – well away from the administration and workshop area where the bomb was alleged to be.

In a statement a BHP Billiton spokeswoman said the company had “suspended operations and evacuated employees as a precautionary measure due to information being received” at its Mount Arthur site.

“Police were notified and the information assessed,” she said.

“Mount Arthur Coal has recommenced operations having deemed it safe to do so.”

NSW Police are investigating leads to discover the instigator of the hoax call.

It has been a difficult few months for Mt Arthur, with employees warned last week that 50 contractor jobs would be put on ice because of a delay in 10 haul trucks being rebuilt.

“BHP Billiton Coal continues to focus on productivity and reducing costs to ensure it remains competitive in the current environment of sustained lower commodity prices and a strong Australian dollar,” a BHP spokeswoman said.

In October last year BHP Billiton reported a collision between a dozer and a light vehicle at Mt Arthur.

A dozer crushed the unoccupied passenger side of the vehicle in the accident.

“Fortunately, no one was injured in the incident and an investigation is underway to determine its cause,” BHP said.

“Following the investigation, any necessary actions will be taken to ensure a similar incident does not occur again in the future.”