A man has been punched in the head on a train after he asked a fellow passenger to turn his music down.

The incident happened on a city-bound train on August 30.

The alleged victim, a 19-year-old, asked the man to turn down his music – which was playing on a Bluetooth speaker.

It’s alleged the man then punched him in the head.

The alleged offender hopped off the train at Glenhuntly, while the victim continued into the city where he called police.

The offender is described as Caucasian, in his late 20s or 30s, wearing a dark cap on backwards, and a red long sleeve checked shirt.

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