Authorities discovered more than 32 dead snakes and goannas in a suburban Darwin unit, after neighbours complained of a bad smell.

"I have never seen anything quite like this before," senior wildlife officer Ray Chatto said.

"I was called to the unit on Wednesday afternoon after reports of a bad smell.

"I found a large number of snakes and goannas, most of which were dead, while those that managed to survive are now being cared for."