All Geelong-bound lanes have reopened on the Princes Freeway at Little River.

A small truck collided into the rear of a van at Point Wilson around 3am, forcing the closure of west-bound lanes on the Princes Freeway for eight hours.

The truck driver, aged in his 60s, has been airlifted to hospital with serious injuries.

The van driver, a 47-year-old man, is under police guard in hospital after officers found drugs in the vehicle.

Image: Department of Transport