Irish Rail say its staff sustained "persistent abuse" from the group involved.
Two young people have been arrested after what's being described as the "persistent abuse" of staff on-board a train.
The anti-social behaviour occurred on the Dublin to Galway service on Tuesday evening.
Two members of the group involved were arrested for public order offences at Athlone Train Station, and have since been released, with a file to be prepared for the Juvenile Liaison Officer.
The remainder of the group were refused onward travel.
Irish Rail is apologising to customers affected by the anti-social behaviour, and is encouraging passengers to be respectful of others.
It also says it has deployed extra security & staff to assist with the large numbers travelling, particularly from the West of Ireland to the Ploughing Championships.