PALMYRA Police are investigating an assault that occurred on Boxing Day on a train travelling on the Mandurah line.
Sometime between 7pm and 7.30pm on Tuesday, a 63-year-old male passenger on the train asked a group of three men to tone down their language.
As the man stood up to exit the train at Canning Bridge, one of the men approached him and began punching him to the head and face.
The altercation continued until another passenger intervened.
As the train neared Bull Creek station, the offender assaulted the victim again.
The men were detained by Transit Officers at the Bull Creek station and removed from the train.
The victim received bruising to his face and ribs.
Police are asking anyone who was on the train that saw the incident to contact Crime Stoppers on 1800 333 000 or report online.