Police are hunting for a man who allegedly performed a lewd act on a bus in Endeavour Hills last month.
The act occurred in the presence of a young woman on the route 845 bus between Linden Place, Doveton and Endeavour Hills about 12.15pm on Monday 14 October, police say.
The man left the bus at the corner of Hanna Drive and Reema Boulevard.
The woman was not physically injured.
Transit CIU detectives released images of a man wanted for questioning on the matter.
He is described as Middle Eastern appearance, between 30 and 45 years, bald and with a brown moustache and beard.
At the time, he was wearing black sunglasses, a green or blue Puma T-shirt and light-coloured jeans.
Any information to Crime Stoppers on 1800 333 000 or crimestoppersvic.com.au