Western Australia's Department of Mines and Petroleum is investigating serious safety concerns at Gina Rinehart's $10 billion Roy Hill iron ore mine.

A mining source said major construction work has been slowed at the remote site since early January.

Gina Rinehart's Roy Hill mine has been served two prohibition notices in response to a number of serious incidents reported in the past year involving cranes and elevated working platforms. Credit:Bloomberg

Department of Mines and Petroleum director of mines safety Andrew Chaplyn said the department had issued two prohibition notices in response to a number of serious incidents reported at the mine in the past year involving cranes and elevated working platforms.

"While no workers were injured in the incidents, the notices were issued as the incidents raise serious safety concerns which the department is investigating," he said.