A man spat at a teenage Celtic fan after shouting sectarian abuse at her and her friends in the aftermath of last weekend’s Old Firm match.
British Transport Police (BTP) said the three teenage girls, all wearing Celtic tops, were travelling on a train which stopped at Old Kilpatrick station in West Dunbartonshire.
Two men on the platform spotted the girls and started to shout sectarian abuse at them before one of the men boarded the train and spat at one of the girls.
One of the suspects was covering his face with a Union Flag patterned scarf. He was wearing a blue top and dark trousers.
The second man was wearing a black T-shirt and shorts and had a dark beard.
The incident happened at about 4.30pm on Saturday, hours after Celtic beat Rangers 5-1 in the first Old Firm league clash for four years.
BTP officers are appealing for information.
Pc Colin Campbell said: “This type of aggressive behaviour is totally unacceptable and will not be tolerated.
“The girls were obviously left very shaken by the incident, which was completely unprovoked.
“I urge anyone who was in the station at the time, or travelling onboard the train, to come forward and help us bring these men to justice.”
Anyone with information is asked to contact British Transport Police on 0800 40 50 40 or text 61016, quoting 399 of 10/9.