The relatively small eye diameter compared to the rest of the head and the rounded head esp. in cross-section as seen in the photo indicates that this specimen is a Small-eyed Snake (Cryptophis nigrescens). Red-bellies have a much larger relative eye diameter and a more distinct canthus rostralis and overhanging eyebrow ridge.
The dropdown menu on this site currently has Rhinoplocephalus which needs changing to Cryptophis.