Detectives from Melbourne Embona are appealing for public assistance following an armed robbery at a CBD convenience store earlier this month.
Shortly after 6.40pm on Wednesday 10 July a man entered the William Street convenience store, near Little Lonsdale Street, and waited for the attendant to serve customers in the busy store.
He then asked the attendant to come to the rear of the store as he had an enquiry about stock.
The man has followed the attendant back behind the counter then threatened her with a knife and demanded cash.
After taking a quantity of cash he left the store and headed north along William Street.
The female attendant was not injured.
The man was wearing a grey jumper, black pants, white shoes and a grey Starter cap at the time of the incident and he is believed to have a distinctive tattoo on his back.
Police have also released a CCTV of a man they wish to speak with in relation to the incident.

Investigators are keen to hear from anyone who can provide information regarding the identity of the male or with further knowledge of the incident.