A homeless man is fighting for life after being found injured on the side of a freeway.

The 35-year-old was found on the Western Freeway, about 200m west of Mount Cottrell Rd in Cobblebank in Melbourne’s west about 7am on Thursday.

He had been walking next to the freeway with bags of belongings, which were found scattered across the road after the incident.

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7NEWS chopper images show a number of items strewn across the emergency lane, including what appears to be a reusable shopping bag.

A passing driver spotted the man and called emergency services, who arrived to find him unconscious.

He was taken to Royal Melbourne Hospital with life-threatening injuries to his upper body.

After undergoing surgery, he remained in the hospital, with no family by his bedside.

Police believe the man was hit by a car that failed to stop but say the impact likely wasn’t at high speed based on the nature of his injuries.

They say the driver may have turned out of Mount Cottrell Rd and merged onto the freeway.

Given it’s a merging lane, it’s possible the driver didn’t realise they had struck someone, police said.

After reviewing CCTV and tracking his movements, police said the man had been walking for about four-and-a-half hours and covered about 9km before the incident.

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

“A crime-scene has been established while the circumstances surrounding the man’s injuries are investigated,” police said.

In addition to searching for the driver, police are also trying to locate the man’s next of kin.

Anyone with any information has been urged to contact Crime Stoppers.