Photo: esperanceexpress.com.au

Investigators have been told a man was approached by an unknown male in the vicinity of a toilet block on Maribyrnong Boulevard about 9.30pm on 29 September.

The males were conversing before the victim was sexually assaulted.

The victim reported the incident to a nearby police station and a patrol of the area was conducted but the offender was not located.

Investigators have released a facial composite of a man they believe may be able to assist with their enquiries.

Anyone with any information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au.