A badly decomposed body has been discovered in a house in Mataura, in Southland.

It is believed to be that of a 66-year-old Mataura resident, who police say may have died as early as January 1, and was not found until yesterday.

Southern District Command Centre Senior Sergeant Brian Benn said the death was not suspicious and it had been referred to the Coroner.

''Police were contacted by a concerned family member who had not heard from him since around new year, and we went and checked the address,'' he said.