A 49-year-old man has been treated in hospital for facial injuries after being attacked by two teenagers on a train in South Lanarkshire.
The incident happened on the 16:44 ScotRail service between Hamilton West and Glasgow Central.
The two suspects boarded the train at Hamilton West and made an anti-social comment towards another passenger.
The victim had glanced over at the pair, who then approached him and began punching him in the head.
They also spat on him, before getting off the train at Blantyre.
The pair were described as being about 15 or 16 years old and both were wearing a similar light green tracksuit.
Det Sgt Dougie Gallacher, of British Transport Police, appealed for witnesses to contact the police.
"This was a seemingly unprovoked assault and we are working tirelessly to identify those responsible," he said.
"As you would expect this was a frightening experience for this victim."