A train guard was reportedly assaulted by a man in Sheffield, who verbally abused her and grabbed her arm.
Police today appealed for witnesses following the incident, which happened on May 18, at around 6.46pm.
British Transport Police said the female employee had challenged the man after he barged past her on board the train.
At this point, it is reported, the man became aggressive towards the woman, abusing her and grabbing her forcibly on the arm.
Police were called but the man had left the train at Sheffield station.
The man is described as white, aged in his 30s or 40s, with short brown hair and a clean shaven face.
He is said to have been wearing blue jeans, a red checked shirt and brown jacket at the time, and was carrying a brown leather bag.
Officers have appealed for anyone witnesses or anyone knowing someone matching the above description to get in touch.
Anyone with information is asked to text British Transport on 61016 or call 0800 40 50 40, quoting reference 527 of May 18. Alternatively, you can call Crimestoppers free and anonymously on 0800 555 111.