Transit Crime Investigation Unit detectives are investigating after a man performed a lewd act on a bus in Eltham in August.
Police were told a man got on a bus on Main Road Eltham and engaged in sexual activity directed at a female about 2.50pm on 28 August.
The 514 service was heading towards Greensborough, and it is understood the man got off at Grimshaw Street.
Investigators have released an image of a man they believe may be able to assist them with their enquiries.
He is perceived to be of Asian appearance, of slim build and has dark hair.
The man was last seen wearing reading glasses, a purple long sleeve button up shirt tucked into black jeans and black shoes.
Anyone who recognises the man or has information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report at www.crimestoppersvic.com.au
