Police are investigating following a theft and assault at a store in Sunbury last month.

Investigators have been told a man entered the Evans St store about 12pm on June 30.

The man spoke to the store assistant about a refund then picked up a cigarette tin and proceeded to walk out the front door without paying.

The assistant followed the man out of the store and when she asked for the item back, she was punched in the face and had her top ripped.

Police have released images of a man they believe may be able to assist with their enquiries.

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