A teenage boy who allegedly punched a train traveller, knocking him unconscious in a dispute at Wollongong station, has been identified to police.

Many people allegedly recognised the teen after seeing video footage of the attack on the Illawarra Mercury's website.

The clip shows the teen slamming the 61-year-old man into the ground at the station's western entrance about 8.35am on Monday.

The man's head connected with a metal Opal card reader as he hit the ground.