The boy, aged nine, failed to disembark at Warilla’s Peterborough School on Thursday morning, and apparently went unnoticed by the driver as the bus was returned to the depot. 

The driver has been stood down, pending the results of an internal investigation. 

The boy remained aboard for more than six hours until the bus was needed for afternoon runs, shortly before 3pm. Once noticed, he was driven back to the school, where staff called for an ambulance.

Paramedics assessed the boy on the William Avenue school grounds, arriving at about 3.45pm. 

NSW Ambulance Inspector Geoff Senior said the boy was found in good health and did not require hospitalisation. 

"All his observations are unremarkable," he said.

A spokeswoman for the Department of Education said staff at Peterborough cared for the boy until he was returned to relatives.

“The school was made aware that one of their students had been locked in a bus at a depot today after the transport company found the child and delivered him to the school this afternoon,” the spokeswoman said, in a statement issued Thursday evening. 

“The Assisted School Travel Program and Employee Performance and Conduct Unit have launched an investigation into the matter and the actions of the contractor.

“The driver in question has been stood down pending an investigation.”

Peterborough school teaches students with moderate to severe intellectual, physical and multiple disabilities, including autism.

The nature of the boy’s disability is unknown.