At around 9pm on July 7 a group of men boarded the TransPennine Express service at Scarborough and started to make loud, racially abusive comments to a family in the same carriage.
During the incident, one of the men then took off all his clothes, which caused distress to other passengers. The group left the train at Leeds station.
Officers from British Transport Police would like to speak to the man in the CCTV image because they believe he may information which could help the investigation.
If you recognise him or you have any information call 0800 40 50 40 or text 61016, quoting 397 of 14 August. Alternatively, ring Crimestoppers anonymously on 0800 555 111.