Three Metro train controllers have been stood down after testing positive for either cannabis or alcohol while on the job.

The staff members, who help manage the city's trains from the company's control centre, tested positive in drug and alcohol tests late last week.

Three Metro train controllers have been stood down.

Metro carried out drug and alcohol tests after a potential safety breach in which a train that was under maintenance moved when it was unsafe to do so. Nobody was injured in the incident.

The three employees who tested positive have now been stood down with pay. It is understood they were long-serving staff.