At some time between 3 and 3.30pm on Friday 17 February, a 12-year-old girl was travelling on the number 3 bus, between Warrington Bus Station and the Manchester Road bus stop next to Beresford Street, when an unknown man inappropriately touched her.
The incident is believed to be isolated and police have been conducting a number of enquiries to trace the person responsible.
As part of their investigation, officers have now issued an image of a man they are looking to identify.
Police Constable John Riley said: “I want to be clear that we are doing all we can to locate the person responsible and do believe this to be an isolated incident.
“We have a number of enquiries ongoing and as part of these, we are now appealing for assistance to identify the man in the CCTV as we believe he may have vital information to assist us with our investigation.
“I would also appeal to the man himself to please come forward. Anyone who believes that they have information about the incident and has not yet spoken to police to please do so by calling us on 101.”
Anyone with information is asked to report it to Cheshire Police by calling 101 or via the Cheshire Police website quoting IML 1481508.
Information can also be provided to Crimestoppers anonymously by calling 0800 555 111 or visit the Crimestoppers website.