A QGC spokesman told EnergyNews the workers were "briefly exposed" to a low level of radioactivity on February 28 from a common measuring device that was owned by Schlumberger.

The rig was operated by Weatherford.

"Our contractor has undertaken an internal investigation to prevent a recurrence and has provided this to the regulator," QGC said.

"Handling of these devices, which are used to determine properties of rock, is strictly controlled by regulations and our contractor's policies and procedures."

QGC said medical examinations were done as a precaution and the worker's health continues to be monitored.

While the incident took place in late February, it was only recently revealed to local media.

The spokesman did not reveal how many rads of radiation the workers absorbed.