The body of a man found dumped a tip at Hampton Park, in Melbourne's south-east, this morning was brought in on a rubbish truck, detectives believe.

A tip worker found the body face down in rubbish at the Hallam Road site around 8:00am.

The employee first thought the body was a mannequin.

Police were yet to identify the man or how he died but Detective Senior Sergeant Shane O'Connell believed he died recently.

"We believe that he was brought in one of the trucks this morning," he said.

"It's very disturbing. No-one deserves to be in the position this gentlemen finds himself in."

A spokeswoman for Sita, the company that runs the landfill, said they were cooperating with police.

The landfill takes general household rubbish, commercial and industrial waste and construction and demolition materials.