British Transport Police have issued a CCTV appeal after a man was left unconscious on a Metro platform.
The appeal has been made after a report of an assault at Brockley Whins station in Tyne and Wear at 8.08pm on Monday 1 April.
BTP said a teenage boy is reported to have been smoking on board the train when he was asked to stop by the victim.
The boy left the train when it arrived at Brockley Whins but stayed on the platform and punched the victim following an argument.
The victim collapsed unconscious on the platform and suffered cuts to his face and mouth and damage to his teeth.
The youth had boarded the train at Monument Metro station in Newcastle.
BTP officers believe the person in the image may have information that could help their investigation.
Anyone who knows him, or who has more information about the incident, is asked to contact BTP by texting 61016 or by calling 0800 40 50 40 and quoting reference 564 of 01/04/19.
Alternatively, call Crimestoppers anonymously on 0800 555 111.