A 12-year-old girl was sexually assaulted on a train travelling to Airdrie. 

The victim was travelling with her mum and sister on the 10.08am service from Balloch to Airdrie on Tuesday, July 25 when she was sexually assaulted by the man at around 10.20am. 

The man is believed to have boarded the train at Dumbarton Central and got off at Old Kilpatrick Station. 

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British Transport Police are now appealing for witnesses to come forward. 

Officers believe a person sat nearby the man may have witnessed the assault and are urging them to get in touch to assist with their investigation.  

The man is described as being white and of average height with a medium build and short greyish hair. 

He was wearing a black mask that partially covered his face, a black hooded jacket, black bottoms with a red stripe down the leg, and black Nike trainers. 

He was carrying a black bin liner and a black rucksack. 

Anyone with information is asked to contact BTP by texting 6106 or calling 0800 40 50 40 and quoting reference number 210 of July 25. 

Alternatively, Crimestoppers can be contacted anonymously on 0800 555 111.