A teenager was reportedly sexually assaulted as she travelled on a bus towards Meadowhall.
The 19-year-old woman was travelling on the X1 bus towards Meadowhall when a man got on at the Wicker pharmacy.
On the journey between the Wicker and Meadowhall it is alleged that he sexually assaulted the woman.
The man is described as being between 40 and 50-years-old, of stocky build, between 5ft 6ins and 5ft 9ins tall, and was wearing navy tracksuit bottoms and a cream cardigan.
Despite extensive enquiries, no arrests have been made and the man has not yet been indentified.
Police are keen to speak to the man in the CCTV images as he may hold useful information.
The reported attack happened between 11.30am and 11.45am on Saturday, August 26.
Call police on 101 quoting incident number 514 of August 26 2017 with any information.