Ribble Valley parents are asked to keep a close eye on their children in the evenings.
The advice has been issued by Sgt Stuart Banks, of Clitheroe Police, after an operation which saw officers join forces with other local agencies to crackdown on anti-social behaviour in the town.
They patrolled the grounds of Clitheroe Castle to remove alcohol from anyone who is found drinking and causing a nuisance.
Sgt Banks said: “Neighbourhood police officers in Clitheroe together with trading standards and officials from the Community Alcohol Partnership patrolled Clitheroe Castle grounds last weekend.
“In particular, the area that generated calls in relation to anti-social behaviour, under-age drinking and drug taking. Officials had occasion to speak to a number of youths, some who were found to be in possession of smoking cannabis. Officers then liaised with the children’s parents and the matter will be directed to the correct service.”