A contract worker servicing a piece of machinery at the Attunga Limestone Mine was trapped under the cab of a loader during a freak accident on the morning of November 30, a report from the NSW Resource Regulator said.

The man suffered upper body injuries when he was crushed, and was taken to hospital for treatment.

An initial report by the watchdog indicated the man was hurt when a piece of equipment suddenly failed and there was no back-up support in use to stop the raised cab of the loader from falling on him.

READ ALSO:

It said a "hydraulic ram" released when the man had finished the job he was working on, causing the weight of the machinery's cab to trap his upper body underneath it when it lowered.

It is understood his cries for help alerted miners in a near-by meal room, who rushed to his aid and worked to free the man before paramedics arrived at the scene.

"A contract maintenance worker entered a crush point ... relying entirely on the single hydraulic strut supporting the cab without using a secondary cabin support device," the preliminary NSW Resource Regulator report reads.

"The hydraulic control system unexpectedly released and the cab descended onto the worker's upper body."

An investigation was launched following the incident, which occurred just after 11am on November 30, by the NSW Resources Regulator to uncover how and why the crushing occurred.

The authority is expected to prepare and release a detailed and comprehensive report when the investigation is wrapped up.

The mining watchdog said it will consider the design of the equipment, the training and supervision of the worker and the adequacy of policies and procedures relevant to the incident, among other issues.

The mine operator, Graymont NSW Pty Ltd., and the injured man's employer are working with the NSW Resources Regulator and cooperating in the investigation.

The initial report stated mine workers and contractors should never place a body part in a crush point under a suspended load without secondary support devices.