Police want to trace this man after complaints that a train passenger was repeatedly touched in a sexual manner.
British Transport Police have released images of him following an alleged incident during a journey between Manchester Victoria and Durham stations.
A spokesman for the force said: "A man is reported to have repeatedly touched a man’s thigh.
"Officers believe the man in the images may have information that could help their ongoing investigation."
The incident is said to have taken place on Wednesday, November 7, at 9.15pm.
Anyone who recognises the man, or who has more information about the incident, is asked to contact British Transport Police by texting 61016 or calling 0800 40 50 40, quoting reference number 463 of 07/11/18.