A murder investigation is underway after a body was found wrapped in material on the side of a busy road in Sydney's west.

A truck driver made the gruesome discovery when he broke down on Homebush Bay Drive near Olympic Park late last night.

Police decided not to unwrap the corpse because they did not want to tamper with any evidence and instead sent it to a morgue.

Detective Inspector Paul Arnold said formal identification was underway but it was still too early to know the age of the victim.

"We strongly require the public's assistance in working out how this man ended up on the side of the road," he said.

"Anyone who has concerns about a loved one not coming home should contact local police and make a missing persons report."

Forensic police officers spent the morning scouring bushland between Bicentennial Park and Homebush Bay Drive.

The mysterious body appears to have been dumped about 200 metres away from a restaurant in the centre of the park.

Restaurant owner Theodore Drivas said the grim discovery has "shocked" locals.

"We have a lot of families and children who come to the playgrounds and who eat at the restaurant — it's an awful thing to wake up to," he said.

Homicide investigators approached business owners in the area to see if they had any CCTV footage from the park.

Results from the post-mortem are expected in the next 24 hours.