Northern Territory Police are investigating a road crash involving a pedestrian and a single vehicle.

Police received a report early this morning from a man travelling to work who believed he had struck an object on the road. After turning his vehicle around to investigate, he located an unconscious man.

St John Ambulance attended the scene and conveyed the injured man to Royal Darwin Hospital, where he remains in a critical condition.

The driver returned negative roadside alcohol and drug test results and is assisting police with their inquiries.

Chibnall Road remains closed while investigators examine the scene.