British Transport Police have launched a CCTV appeal after a group of football fans engaged in racist chanting on a packed Lincoln-bound train.
Officers are searching for the man captured on CCTV, who they believe can help with investigations.
The incident occurred on Saturday, March 5 shortly after 8pm as the train, packed with families, was travelling between Woodhouse, Sheffield and Retford.
Investigating officer PC Dermott Carlin said: “A group of around five football fans, believed to be Sheffield Wednesday supporters, were travelling on the 7.49pm Northern Rail service from Sheffield to Lincoln and chanting racist songs to the obvious distress of fellow passengers.
“We are keen to hear from anyone who might have witnessed this anti-social and racist display.
“Loutish and racist behaviour like this has no place on the rail network and will not be tolerated.”
“I believe this man (pictured) will have vital information which could greatly assist our investigation. Who is he?”
Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference 241 of March 15.
Information can also be passed anonymously to the independent charity Crimestoppers on 0800 555 111.