Duck with knife in head in SA park: RSPCA

The RSPCA has received reports of a duck with a knife embedded in its head in the Adelaide Hills.

The animal welfare group says it received three separate reports, two of which were accompanied by pictures, about the duck at Byethorne Park in Nairne on Friday, calling it "an appalling, deliberate act of cruelty".

RSCPA rescue officers have searched the park but have not been able to find the duck, and the authority is urging anyone who may see it to contact them.

A Facebook post about the bird from RSPCA South Australia has raised more than 800 comments, mostly of outrage and occasionally scepticism.

"Absolutely disgustingly cruel people out there. The poor duck," one woman commented.

"Looks photoshopped," another man wrote.

RSPCA SA chief inspector Andrea Lewis says the agency has spoken with two of the people who made reports and had "no reason to believe the images were fake".

"RSPCA South Australia takes every report of cruelty seriously and this incident is no different," she said in a statement on Tuesday.