"Spy kids" will be used to crack down on the practice of selling cigarettes to under 16s in a pilot scheme launched by Scotland's top law officer.

It is the first time their evidence could be used to prosecute culprits.

But the Scottish Human Rights Centre said it was concerned about the children's welfare and one newsagent argued it was "entrapment".

A child that is almost 16 is going to be used as a guinea pig to try and trap newsagents and retailers into selling tobacco Peter Meldrum Newsagent

The pilot project will run in Stirling, Edinburgh, Moray and South Ayrshire.

It is estimated 30% of 15-year-olds in Scotland smoke regularly.

A previous scheme in Stirling revealed about a third of the city's retailers willingly sold cigarettes to underage volunteers.

Lord Advocate Colin Boyd has now given permission for 13 and 14-year-olds to be used to catch retailers.

Trading standards officers

Accompanied by trading standards officers, they will pose as customers.

Retailers will be warned initially and if they continue to flout the law they will be prosecuted, using evidence from children for the first time.

Trading Standards manager Neil Chalmers said other measures taken to deal with the problem had failed to make an impact.

The sting operation has divided opinion

He said: "The children are volunteers, understand what's involved, have parental consent and backing from the education services.

"We've had the legislation on our warrants for a number of years now and carried out surveys, had proof of age cards introduced but there is still a problem with regards to the sale of tobacco."

Newsagent Peter Meldrum criticised the move and said it amounted to "entrapment".

He said: "It is entrapment when someone comes in with a child or use children that are borderline cases.

'Witness box'

"A child that is almost 16 is going to be used as a guinea pig to try and trap newsagents and retailers into selling tobacco."

John Scott, chairman of the Scottish Human Rights Centre, said he was unconvinced trading standards officers could adequately protect children.

He said: "The protection that they can afford to children in the witness box is very limited.

"In the witness box he or she is on their own and accusations can be put of what was said to shopkeepers.

"There is nothing that can be said to protect them from having to answer those questions."

However, Maureen Moore of anti-smoking body Ash Scotland, welcomed the pilot ptojects.

She said: "These pilots are an enormous step forward.

"About one in five of all 13-year-olds in Scotland smokes and the overwhelming majority of child smokers get their cigarettes from shops.

"Test purchasing will provide a real deterrent against those retailers who persistently break the law by peddling tobacco to children for the first time."

There is pressure to extend the scheme to cover alcohol and lighter fuel.