Transit Crime Investigation Unit detectives have released an image of a man following a sexual offence on a train last month, Victoria Police say.
Officers have been told a man boarded a Hurstbridge bound train which departed Flinders Street at 5.55am on Friday 25 May.
The man allegedly commenced masturbating in the presence of a female commuter while travelling between Montmorency and Eltham, about 6.40am.
The female fled the train at Eltham and reported the incident to police.
Detectives have released an image of a man they wish to speak to in relation to the incident.
He is described as being aged between 20 and 30 years, perceived to be of Caucasian appearance, with a medium build, short light brown hair and unshaven.
At the time he was wearing two hooded jumpers and a backpack.
Anyone with information about the man is urged to contact Crime Stoppers.
