British Transport Police (BTP) officers are appealing for the public's help to identify three people they would like to speak to in connection with the theft of a mobile phone from a passenger on board a train travelling between Swindon and Gloucester railway stations.
Officers have released CCTV images of two women and a man they believe will have information which can assist the investigation into the incident which took place on Saturday, January 12.
PC Frank Hedley, investigating officer, said: "The 15-year-old female victim boarded the 6.14pm Swindon-Gloucester service at Swindon station on Saturday, January 12.
"A man and two women sat behind the victim on the train and during the journey, the victim noticed her Blackberry Curve mobile phone was missing.
"After reviewing CCTV images and speaking to witnesses, I would now like to speak to the three people in these images as I believe they will be able to assist with our enquiries.
"If you have any information, I would ask that you contact BTP straight away."
Anyone with information is asked to contact British Transport Police on Freefone 0800 40 50 40, or the independent charity Crimestoppers on 0800 555 111.
In all calls, please quote incident reference B8/WWA of 14/02/2013.