The initiative is part of a package of measures aimed at curbing the sale of alcopops to youngsters and includes new powers for the police to confiscate alcohol from under-18s drinking in public.
It will also become an offence for adults to buy alcohol from a shop or off-licence for an unsupervised youngster.
But the Government has drawn back from banning alcoholic lemonades such as Hooch and Two Dogs, preferring instead to give the brewers and shopkeepers a final chance to curb under-age drinking.
A ministerial team yesterday backed a revised code of conduct for retailers and drinks makers drawn up by the Portman Group, the drinks industry's self-regulating watchdog.
Under the terms of the new code retailers will be urged not to stock alcopops or any other alcoholic drinks deemed to be targeted at under- 18s.
The group has also pledged to expand its ID cards and encourage retailers to insist they be shown at shop tills, although there are doubts that such a voluntary system will work.
The code will also require manufacturers to have their products vetted by its complaints panel before they are launched.
George Howarth, Home Office minister, criticised alcopop makers yesterday, saying: "It's a cynical attempt to snare people are a very early age" which could lead to a life of crime.
The joint initiative follows a chorus of complaints about the packaging and advertising of the fruit-flavoured alcoholic drinks which have become popular with under-age drinkers.
The main measures announ-ced by the Government are an expansion of the use of teenage "spies", often children of police and trading standards officers, who are used to test whether shopkeepers are breaking the law. At present, the police and trading standards have been reluctant to use this technique very often because of uncertainty about whether it could be challenged in the courts. The Government plans to introduce legislation to clarify the position.
The second initiative is the implementation of police powers to confiscate alcohol from under-18s caught drinking in public. The measure, already on the statute book from the last government, should be in use by early next month.
In a third change, it will become illegal for adults to buy alcohol for youngsters - already an offence in Scotland. However, Mr Howarth added: "We are not trying to stop parents who want to give their children a glass of beer or wine with a meal."
The Magistrates' Association is backing the initiative and urging licensing authorities to take into account whether a retailer has followed the code of conduct when deciding whether to renew his licence.
But Alcohol Concern campaigners said they are worried the measures do not go far enough. Its director, Eric Appleby, said: "They will do little to discourage rogue manufacturers from launching products in which they have invested millions of pounds."Reuse content