A hit-and-run victim found dead on the F3 after he was dropped off on the busy freeway has been identified as a Sydney man, police say.

Police said the man was a 33-year old from Quakers Hill and officers were continuing to investigate the circumstances of his death.

It is believed the man got out of a car near the Kariong exit about 8.45pm on Tuesday, before he was struck and killed by another vehicle.

A driver has told police he dropped a man off about the same time.

Another motorist reported seeing his remains scattered on the freeway just before midnight and police spent Wednesday morning searching the area, forcing the road to be closed for several hours.