British Transport Police (BTP) detectives are appealing for information following an attempted sexual assault on a woman at Ystrad Mynach railway station in the early hours of Tuesday January 4.
Officers have also released a CCTV image of a man they would like to speak to in connection with the incident.
Shortly before 1am on Tuesday January 4, the 29-year-old victim was on the station platform when she was approached by a man who tried to attack her but she managed to fight him off.
Detective Inspector Mark Cleland said: “A full investigation is under way and the station was cordoned off for a time while a crime scene examiner gathered forensic evidence.
“At this stage, I would like to appeal to members of the public who may recognise the man in the CCTV image to come forward.
“The man we would like to speak to is described as white, aged 20 to 30, of average height and build, with short dark hair and buck teeth. He was wearing a long-sleeved top and jeans.
“We believe he may have travelled on the 10.49pm Penarth to Ystrad Mynach service on Monday January 3, which arrived at Ystrad Mynach at 11.45pm, so I would also appeal to anyone who was on that train and may have saw the man to come forward.”
DI Cleland added: “This sort of attack is extremely rare and, thankfully, the victim was not seriously injured.
“However, this is a serious crime and I would appeal for anyone with information to come forward as soon as possible.”
Anyone with information is asked to contact BTP on 0800 40 50 40, quoting incident number 13 of 04/01/2011, or Crimestoppers anonymously on 0800 555 111.