In footage uploaded to YouTube, the man calls another passenger a “monkey” and a “gorilla”, and threatens to glass him with a beer bottle.
Other passengers try to placate the man, who appears heavily intoxicated, and urge him repeatedly to sit down and calm himself. Brandishing a bottle, the man tells a passenger: “See that, I will shove that in your fucking eyes.” He adds: “I don’t like being rudely awakened by a mongrel.”
The man, who speaks with a strong Irish accent, goes on to say he is not racist, during the nearly three minutes of footage.
British Transport Police (BTP) said they take this type of offence seriously as they appealed for witnesses to the incident on a train near Brighton on May 26.
Train operator Southern said rail neighbourhood officers (RNOs) at Brighton received a call from a conductor to help remove a man from his train.
The man was cautioned for fare evasion and his details were taken but the alleged victim did not want to pursue the matter.
A Southern spokesman said: “One of the RNOs also took a statement from a witness who showed him a short clip of what had taken place on the train.
“The alleged victim did not want to pursue the matter and left the station without giving his details. Bearing this in mind, the RNO decided it did not warrant a 999 call, but reported the incident to his BTP co-ordinator.”