Police are seeking information after a video has emerged online showing an elderly man being repeatedly punched in the face on a London Underground train.

The video shows the elderly man and a younger man struggling, with the elderly man hitting the younger man. The younger man then appears to get frustrated and starts punching the elderly man repeatedly in the face until he falls unconscious.

British Transport Police have released a photograph of the younger man, and are looking for help identifying him.

Detective Constable Lawrence Murphy said:

“At 9.20pm onboard a District line train, a physical altercation occurred between two men which resulted in a fight which left a man requiring hospital treatment.

I urgently want to speak to the man pictured, as I believe he will be able to greatly assist the investigation. If you recognise him, or were on board the train, please get in touch.”

Anyone with information is asked to call 0800 40 50 40, or text 61016, and quote B4 of 29/04/2014. Information can also be passed to the independent charity Crimestoppers on 0800 555 111.