Photo: vicpolicenews

The incident took place on Chesterville Road on Saturday 24 June at 12.40pm.

The victim, a 15-year-old girl, who has an intellectual disability, was walking along Chesterville Road when she was approached by a man.

The man had a short conversation with the victim before sexually assaulting her.

Investigators have released security footage and a computer generated image of a man who they believe can assist with their enquiries.

The man is perceived to be of Caucasian appearance, aged between 30-40years, short brown hair, unshaven and wearing a baseball cap.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000 of file a confidential report at www.crimestoppersvic.com.au.