Homicide detectives are relying heavily on the work of forensic experts to identify a man whose charred and dismembered body was found in grassland last week.

Rural firefighters found the man's body after extinguishing a grass fire on the side of Cedar Pocket Road near Gympie, north of Brisbane, about 6.45pm on Thursday.

Detective acting Superintendent Darrin Shadlow confirmed the man's body was found decapitated and with both arms removed below the elbow. The lower part of the man's body, beneath his rib cage, was also missing.

Cadaver dogs searched the crime scene at the weekend, but none of the missing body parts have been found.