A train guard was hit with a bottle of alcohol thrown by a passenger on a train travelling between Edinburgh and Dundee.
The incident happened at 7.20pm on March 2 when anti-social behaviour led the guard to ask a group to leave the service at Inverkeithing, Fife.
British Transport Police (BTP) said they then became aggressive and a container was thrown at him then a glass bottle, which smashed off the train doors.
One of the men involved is described as white, approximately 20 years old and of slim build.
He was around 6ft 2ins tall, clean-shaven and wearing a brown flat cap, pink/white t-shirt, short jacket and navy jeans with white trainers.
Anyone who was on board or has information is asked to contact BTP by sending a text to 61016 or call 0800 40 50 40 quoting reference 602 of 02/03/2019; or call Crimestoppers anonymously on 0800 555 111.