It follows an incident on Friday evening.
Detectives from the PSNI’s Reactive and Organised Crime Branch based at Ardmore PSNI station in Newry are investigating.
Detective Sergeant David Cameron said: “A 33 year old man was driving his car near Kilkeel when he was stopped by a ‘road closed’ sign and two men wearing hi vis jackets.
“They proceeded to take the driver’s car keys and then assaulted him while he was in the passenger seat of the car.
“He was subjected to this ordeal while one of the men drove around with the other in the back seat.
“The victim was eventually returned close to the spot where he was stopped originally and was then left at the side of the road.
“The men demanded his mobile phone before driving off in his car.
“Police later recovered the stolen car and mobile phone from an address in east Belfast.”