Detectives are appealing for witnesses to come forward after two men were injured in a fight on Waterloo Station's concourse.
Detective Constable Rachel Smith said: "Two men got into a fight after which they both required hospital treatment for their injuries.
"We need to speak to anyone who saw what happened to build a clear picture of events surrounding this incident.
"The fight took place outside Foyles and we know several people saw what happened.
"Please get in touch if you have any information."
Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference SSUB/B5 of 17/12/15. Information can also be passed anonymously to the independent charity Crimestoppers on 0800 555 111.