An angry passenger assaulted a rail worker after he was told his Oyster card was not working.
Detectives from British Transport Police are appealing for information after the man pushed the worker over and stole a cash bag.
The incident happened at about 8.50am on Saturday December 28 at Clapham Junction railway station.
Police are now releasing images of the man they want to speak to in connection with the incident.
Detective Constable Mark Agrippa, the investigating officer, said: “A man got into a dispute with a member of rail staff after he was told that his Oyster card was not working.
“The man put his hand into the victim’s pocket and took out a mobile phone, a set of keys and a cash bag.
“He then pushed the member of staff and went through the gates before throwing the mobile phone and keys at the victim.”
Det Con Agrippa added: “The man ran out of the station with the cash bag and we believe he started his journey at Thornton Heath station.
“I’d urge anyone who recognises the man, or has information that could help officers with the investigation, to please contact us.”