Passengers suffered homophobic abuse on a train in an incident described by police as “serious public disorder”.
The passengers were on the ScotRail service that left Aberdeen station at 5.09pm on Tuesday headed for Edinburgh.
A group of men started harassing the passengers and British Transport Police officers were called to the scene at about 5.30pm, shortly before the train was due to arrive at Laurencekirk.
British Transport Police spokesman said: “Three men have since been spoken to and details have been taken but we are now looking for any witnesses who may be able to help with our ongoing enquiries.
“Anyone who witnessed the incident or who has any information about what happened is asked to contact BTP on 0800 40 50 40 or text information to 61016, quoting reference number 218 of 27/07/2017.”