British Transport Police has released CCTV images after a man was ‘repeatedly punched in the head’ on a train.
Police said the incident, on the 10.33pm service from Brighton to London Victoria, took place at around 10.50pm on Tuesday, July 3.
The fight appeared to be over a cookie, police said.
Police said there was an exchange between the victim and a group of nearby men, which was initially friendly. They threw a cookie at him, which he threw back.
Two of the men then came over and punched him in the head and face, until a member of the public intervened, police said.
The man left the train at Three Bridges and was seen in hospital, suffering swelling and bruising to his face.
Officers have released images of two men they believe they may have information which could help the investigation.
Anyone with information is asked to contact BTP by calling 0800 40 50 40 or texting 61016 with reference 712 of July 3.