The incident happened on a service from the Midlands, following a game against Birmingham City, on April 26.
PC Gareth Swiffen, of British Transport Police, said; “We received reports from a number of members of the public that the group were rowdy and boisterous throughout the journey – swearing, chanting and singing abusive songs.
“One member of the group was also extremely aggressive to a police officer on board the service.”
Officers have now released a CCTV image of a man they are still looking for as the sides prepare to meet again on Saturday.
PC Swiffen added: “Others on the train, who should have been able to travel without encountering this sort of behaviour, have said they were disgusted by the actions of this group.
“Their behaviour was vulgar and offensive, leaving fellow passengers – including young children – feeling uncomfortable and intimidated.”
Anyone with information should contact British Transport Police on 0800 405040, quoting reference PSUB/B3 of September 11.