The Office of Tobacco Control is to step up its use of teenage volunteers to police the illegal selling of cigarettes to people under 18.
Under legislation updated in 2001, health boards, in co-operation with the OTC, can engage the assistance of minors to buy cigarettes in an attempt to expose retailers selling tobacco products to children.
A spokesman for the OTC said it takes around 20 successful prosecutions a year through this method.
However, it now intends to increase its efforts in an attempt to stamp out illegal sales.
"Up to now the main focus has been on the smoking ban, but the sale of cigarettes to children is going to be the next big focus of effort. We will be ratcheting up our efforts on this issue, once the smoking ban is bedded down."
Preventing young people smoking was a "major concern" of the OTC, he said.
"The workplace smoking ban will have a great impact on people's health, but if we could prevent people smoking in the first place, that would be even better."
Most shopkeepers were obeying the law, he added, but it was now a matter of securing compliance among the entire trade.
The national inspection programme, operated by environmental health officers and child volunteers, has been developed since selling cigarettes to those under 18 was made illegal in 1998, according to Ms Anne Marie Part of the Environmental Health Officers' Association.
The programme is subject to a strict protocol, Ms Part said, to ensure that children are never left unaccompanied and that there is no entrapment of retailers.
"We have no qualms about this method. We aren't trying to trap people and generally proprietors will have had warnings before it comes to this stage."
The volunteers must have consent from their parents to take part in any operation. They must dress appropriately for their age and must not try to look older than they are.
When approaching a shop, they are accompanied by two environmental health officers, one of whom waits outside the premises while the other is in the shop to witness any transaction taking place.
If asked their age by the retailer, the volunteer must tell the truth. If they are sold cigarettes, they must immediately give them to the environmental health officer outside, who will keep the packet as evidence.
Volunteers are never asked to buy cigarettes in their local shops.
They are not paid, but may be given "a small token of appreciation", Ms Part said.
"We treat the sale of cigarettes to minors with the same degree of gravity as the sale of a bottle of whiskey or an X-rated video."
