Scout leaders have been told to give condoms to the teenagers in their troops and consider trips to family planning clinics.
In new guidance the Scout Association says leaders should provide condoms “if they believe the young person is very likely to begin or continue having intercourse with or without contraception”.
Much of the guidance deals with the 14 to 18 age group, although it says that younger scouts should be provided with information about sexual health and contraceptives if they ask for it.
Critics say the policy marks a major shift from the scouts’ 100-year-old Christian ethos.
Chief Scout Peter Duncan commented: “We must be realistic and accept that around a third of young people are sexually active before 16 and many more start relationships at 16 and 17.
“With over 450,000 members Scouting touches members of every community, religious and social group in the country so adults in Scouting have a duty to promote safe and responsible relationships and as an organisation we have the responsibility to provide sound advice about how to do that.”
Family groups have responded with dismay to the plans.
Margaret Morrissey of Parents Outloud said: “The last people you would expect to be making children sexually aware is the Boy Scouts.
“They should stop trying to be politically correct. All the signs are that political correctness has got us in the situation we’re in now where young people are trying to grow up too soon and can’t cope with it.
“They’re confused and do things they probably wouldn’t have done if they hadn’t had that information in the first place. If we overload young children with information they will use it in the wrong way.”
Norman Wells, director of Family and Youth Concern, added: “Learning about contraception in local Scout groups gives the impression that young people are expected to be sexually active and that there is nothing wrong with teenage sexual experimentation.”
Ann Widdecombe, the Conservative MP, said: “This is not what parents expect of the Scout Association. They are sending their children off to a leisure activity, not for sex education.
“This is a matter for parents and they already find their role usurped by schools. They certainly do not need the scouts doing it as well. It is up to parents to control the pace of revelations, not the scouts.”