British Transport Police officers investigating an assault on board a train at Liverpool James Street station have released a CCTV image in connection with the incident.
Shortly before 10.50pm on Saturday 19 August, the victim was travelling on a Merseyrail service which had reached James Street station when she was punched by a stranger several times to her face.
The assailant then left the train.
Detectives believe the man in the CCTV image may have information that could help their investigation.
Anyone who recognises him is asked to contact BTP by texting 61016, or by calling 0800 40 50 40 quoting reference 2300097746.
Alternatively, call Crimestoppers anonymously on 0800 555 111.