Police have discovered a body decomposing in the boot of a car in western Sydney.

The person, found this morning on East Street in Lidcombe near Rookwood Cemetery, had been dead for about two weeks, police said.

Crime scene: Police have closed off a section of East Street Credit:Marcus Strom

"Police were responding to a complaint about a car being abandoned," a police media spokeswoman said.

"They showed up, had a look, and there was a body in there."