MONMOUTH police are appealing to an elderly gentleman who confronted a group of youths at Somerfield car park on Monday to come forward.
The incident happened at around 6pm when the man confronted five youths who had taken a couple of shopping trolleys and thrown them in the river.
The group turned on him, throwing stones and shouting abuse.
The elderly man did not report the incident but the officer dealing with the case, PC Eddie Roberts, is appealing to him to contact Monmouth Police Station.