A man unleashed a torrent of abuse - for 90 minutes - after being asked to turn down the volume on his phone by a fellow train passenger.
The man, who was playing on his phone, became aggressive towards the male passenger during the incident on a Virgin Trains service from London Kings Cross to Leeds.
A British Transport Police spokeswoman said: "He started verbally abusing the victim, making him feel uncomfortable and threatened. The torrent of abuse continued for approximately 90 minutes.
"Officers are releasing a mobile phone image of a man they’d like to speak with in connection. Do you know who he is?"
The incident took place on the 9.35pm service on Friday, December 9.
Anyone with information is asked to text 61016 or call 0800 40 50 40, quoting reference 300 of 06/01/2016.
Information can also be passed to Crimestoppers anonymously on 0800 40 50 40.