Violent outburst on Adelaide train caught on camera

Police are investigating a violent incident on board an Adelaide train last night.

Mobile phone video shows a man allegedly punching a fellow commuter three times before stepping off the city-bound train on the Seaford line around 6pm.

The man appears to scratch graffiti onto a window and verbally taunt passengers, telling one: "your missus [sic] looks like a prostitute".

Another passenger was allegedly racially abused.

9NEWS has provided a copy of the video to police, who are investigating the incident and are appealing for anyone on the train from Seaford to the city to come forward.

It follows another concerning incident on a bus two weeks ago, where a woman was reported for racially abusing fellow passengers.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000.