British Transport Police is releasing this image in connection with a report of sexual assault on a train from Leicester to Sheffield, via Derby.
The incident happened between 1.00pm and 1.10pm on Tuesday, 5 September.
The victim boarded the service at Leicester.
Shortly after, another passenger entered the same carriage and stood in the seat directly behind the victim.
He then leaned over the chair and repeatedly touched her inappropriately.
The victim then left the carriage, and the other passenger left the service at Derby.
Detectives would like to speak to the man in the image as they believe he may have information that could help their investigation.
Anyone who recognises him is asked to contact the British Transport Police by texting 61016 or by calling 0800 40 50 40 quoting reference 302 of 05/09/2023.
Alternatively you can call Crimestoppers anonymously on 0800 555 111.
