Boris Johnson’s youth strategy ran into immediate problems yesterday when the Scouts and Girl Guides refused to co-operate with his plan to force young offenders and troubled teenagers to join their ranks.

The London Mayor’s blueprint to divert youth from crime calls for compulsory attendance at structured youth organisations to build “self-respect and character”.

“Working with the police, the Probation Service, the Parole Board and London Councils, we want to use our powers to compel attendance at these organisations by those who need it,” it reads.

“Scout troops and Army Cadet Squads are the kind of gangs we like.”

However the policy, launched yesterday, hit a stumbling block when both the Scouts and Girl Guides said that, as voluntary organisations, they would not work with young people who were forced to join.

Simon Carter, a spokesman for the Scouts, said: “The bottom line for us is that we want to work with young people, whatever their background. But forcing them to join just isn’t what we are about.”

Earlier Kit Malthouse, the deputy mayor for policing, told The Times there should be a “requirement” for young offenders to join such organisations as they built character.

He said that such groups built discipline and would place young offenders on the right path.

“Locking up one young person costs £90,000. If we can invest one third of that in them the first time they offend, we’re also saving the taxpayer money.”

Mr Johnson’s strategy, Time for Action, set out a series of grassroots measures aimed at targeting youth before they fell into lives of crime.

The Mayor conceded that many of the proposals were beyond his jurisdiction, but said that he would work with the relevant authorities to ensure they came to fruition.

“Our job is to encourage and persuade and unite and to mobilise public support,” he said.

Youth crime and related issues formed the basis of Mr Johnson’s mayoral campaign earlier this year. With 27 teenagers murdered in the capital earlier this year, he will be judged at the next election on its success.

However, he stressed that the strategy was not just about knife crime.

“Knife crime is perhaps at the apex of a great pyramid of disorder which is being caused by kids growing up without the opportunities that we need to give them,” Mr Johnson said.

The mayor heralded a generation of “Mayor’s Scholars”, promising to fund literacy and numeracy tutoring for deprived children in care, ensuring that they were steered in the right direction.

His strategy also included anti-truancy measures and plans for several city academies in deprived neighbourhoods.

Mr Johnson also called for first-time offenders to be held separately from “career” criminals to ensure they were not encouraged to continue offending. He promised extra educational support for young offenders so that they were better equipped to deal with life outside jail.

“It is vital that we address the soaring levels of re-offending and the ridiculous situation where first time offenders are more likely to leave custody and commit crime than find a job and contribute to society. We must also do much more to give all children a decent start in life.”

Times Recommends

• An officer and a gentle woman
• Dame Helen Mirren is worthy of the Epidaurus
• Foods that can help to prevent swine flu