A public appeal for help has been made after a homeless man was fatally struck by a vehicle on a Melbourne freeway and left for dead.

The 34-year-old man was found critically injured on the Western Fwy at Cobblebank in the city’s west on May 8.

He had collapsed near the freeway merging lane about 200m west of Mount Cottrell Rd and his bags of belongings were found scattered across the road.

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The man was taken to hospital and underwent surgery but he died on Monday.

It’s believed the man was hit by a large vehicle, which did not remain at the scene following the accident.

Police have not been able to locate the driver responsible, and the make, model and colour of the vehicle involved is unknown.

Detective Senior Sergeant Luke Miller said the vehicle would have sustained some sort of damage in the incident.

Depending on the kind of vehicle that was involved, it’s possible the driver may not have realised they hit someone.

“You would think that if they didn’t know at the time, they would see some damage on their vehicle and be able to understand that something’s occurred even if they’re not aware of it,” Miller said.

The victim was walking for four-and-a-half hours, covering about 9km, before he was struck by the car, CCTV footage of his last movements show.

He was last seen at about 2.30am at a 7-Eleven in Truganina, next to the freeway, where he bought food and drinks.

Miller said a family member of the man was “devastated”.

“‘The impact is not just on the victim but on their friends and family as well who will always feel that trauma.”

Investigators are keen to speak to anyone who was driving between Mount Cottrell Rd and Ferris Rd at the time.

Those with information should contact Crime Stoppers.