A 22-year-old Dunedin man was arrested and charged after driving off in an ambulance while paramedics treated his injured friend last night.

Senior Sergeant Steve Aitken said the man called for an ambulance when his 27-year-old friend fell four metres over a concrete wall, fracturing his skull and vertebrae, in Dunedin at 11pm.

While paramedics helped his friend, the 22-year-old man drove the ambulance 50 metres down the road.

Mr Aitken said one of the ambulance drivers managed to catch up with him, tell him to stop and get out of the vehicle.

Alcohol could be a significant factor, he said.

The man was arrested and charged with unlawfully taking a motor vehicle and driving with the excess breath alcohol.

His friend was taken to Dunedin Hospital.