A member of rail staff was punched during a “violent” ticket altercation at Halifax railway station.
The incident took place on Tuesday, July 28, just before 9am.
Officers are now appealing for the public’s help to identify a woman who they would like to speak to in connection with the assault.
PC Beth Middleton, leading the investigation, said: “A woman approached the ticket barriers and was asked by the member of rail staff, a 22-year-old local man, to show her ticket.
“At this point the woman became extremely aggressive and punched the man in the arm before leaving the station.
“This was a violent and unprovoked assault on a member of rail staff who was simply doing his job; no-one should have to be subjected to such behaviour.
“We would like to speak to the woman pictured in connection with this incident, if you recognise her or know her current whereabouts please contact us.”
Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference PSUB/B10 of 26/8/2015.
Information can also be passed anonymously to Crimestoppers on 0800 555 111.