Trading Standards in Darlington is taking action against two off-licences for selling alcohol to children.
Test purchases were carried out at eight premises last week, six of which refused to sell alcohol to youngsters.
Retailers caught selling alcohol to children can be fined or have their licences revoked.
The operation was carried out alongside a police clampdown on underage drinking, which saw wine, vodka, lager and cider confiscated from youngsters.
Bill Dixon, Darlington Council's cabinet member for neighbourhood services and community safety, said: "The alcohol that these young people are caught with has to come from somewhere, so I'm really pleased that a couple of the premises which are selling it to people who are underage have been caught out, so action can be taken."