BRITISH Transport Police investigating a sexual assault on a train in Powys have released a CCTV image and named a man they want to question.
Mark Geoffrey Ball, 39, is believed to be living in the Aberystwyth area, but is thought to spend time in Shrewsbury, Oswestry and Weston Rhyn in Shropshire.
The alleged assault is said to have happened on a service between Caersws and Machynlleth on 12 August.
Officers said a man sat next to a 24-year-old woman and harassed her.
Sgt Karl Anderson said: "BTP is treating this incident, which took place as the train travelled between Caersws and Machynlleth rail stations, as a sexual assault.
"CCTV inquiries have identified a man, Mark Geoffrey Ball, aged 39, who we would like to speak to about this incident.
"I would urge anyone who knows his current whereabouts to contact British Transport Police in confidence straight away."
People with information is asked to contact British Transport Police on 0800 40 50 40, quoting incident number 605 of 12/08/2010, or Crimestoppers anonymously on 0800 555 111.