Melbourne East police are hoping to identify a man following a sexual assault at a shopping centre in Melbourne last month.
A woman was travelling on an escalator inside the Swanston Street shopping centre when the incident occurred about 3.25pm on 17 August.
Investigators believe a man gestured for the woman to step on the escalator before him, and when she did, he smacked her buttock cheek and began laughing.
The woman quickly exited the escalator and reported the incident to security.
When they approached the man, he took off and ran towards Little Lonsdale Street.
Investigators have released images of a man who they believe may be able to assist with their enquiries.
He is perceived to be Caucasian in appearance, aged 20-30-years-old, with a medium build, dark brown hair and had a distinctive tattoo on his right ankle.
He was wearing a black hooded jumper, dark shorts, black slip on shoes and was carrying a black backpack with brown leather straps.
Anyone who can identify the man or with any information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au