A 20-year-old man has died after being struck by a truck on the Pacific Motorway near Pimlico.

Emergency services were called to the M1 about 5.50pm yesterday, around 2km south of Pimlico Road, following reports of a crash.

Police said the man had exited a vehicle stopped in the breakdown lane before allegedly entering the roadway, where he was hit by a truck.

NSW Ambulance paramedics treated the man at the scene, but he could not be revived.

He has not yet been formally identified.

The north-bound lanes were closed for several hours last night as officers from Richmond Police District established a crime scene, which was later forensically examined.

The truck driver, a 32-year-old man, was not injured. He was taken to Ballina District Hospital for mandatory testing.

Police will prepare a report for the Coroner.

Investigations into the circumstances of the crash are ongoing.

Anyone with information or dashcam footage from the area at the time is urged to contact Ballina Police or Crime Stoppers on 1800 333 000.