A man who was killed when he was thrown from his car when it hit a truck on the Southern Motorway in Auckland early this morning has been identified and police are trying to contact next of kin overseas.

Emergency services were called to the scene just after midnight and the motorway was temporarily closed between the Princess St on-ramp and Mt Wellington Highway off-ramp.

Police say the person was the sole occupant of the car and he was found dead at the scene.

The man was aged in his early twenties.

Police say he was ejected from the vehicle and they're trying to determine whether he had been wearing a seat belt.