Two men have been killed in separate highway crashes in South Australia less than four hours apart today. A man was killed after a car and truck collided on the Old Sturt Highway at Barmera, north-east of Adelaide, this morning.

Emergency services were called to the scene at the junction of the Sturt Highway just before 9am to find the male driver of the car seriously injured.

The truck driver was uninjured.

Traffic was diverted away from the area earlier with motorists advised to take alternate routes.

Less than four hours later, a motorcyclist was killed in the Mid North when he crashed into a car at high speed near Burra.

Traffic restrictions apply at both crash scenes.