Education bosses in Birmingham are developing a five-year plan to put a smile back on the faces of city schoolchildren who are said to be more miserable and prone to depression than anywhere else in the country.

The city council's Brighter Future for Children and Young People Strategy aims to tackle relationship problems from the age of nine months until leaving school and transition into adulthood.

A 41-page document drawn up for the council by social research organisation Dartington-i states that a significant proportion of children in Birmingham have difficulties with relationships and in "doing things that help others".

The report adds: "As the city's children grow older, their behaviour lags behind that in the rest of the UK. Young people in the city appear to be less happy and have more peer problems than children elsewhere in the country.

"Rates of probable conduct disorder and emotional problems are significantly higher here, a particular cause of concern since rates in the UK are already elevated compared with other developed countries."

A fifth of Birmingham school children have difficulty "staying the course" and a smaller proportion are vulnerable to social exclusion by leaving home, quitting school and getting into trouble with the law, according to the report.

Problems are described as being driven by socio-economic factors, including poverty, unemployment, high levels of teenage pregnancies and obesity. Pre-school children in Birmingham tend to be less energetic and lively than children in England as a whole, although fitness levels are likely to improve as they grow older.

The new strategy aims to treat all children equally by building support services for age groups from birth to aged 25. The recommendations were drawn up following the collection of data in Birmingham and around the world, with contributions from more than 200 experts from city children's organisations.

The document adds: "The strategy was much influenced by experts who stressed the association between good outcomes and children remaining in the mainstream of society.

"Reducing the number of children separated from home, excluded from school or drawn into the youth justice system will underpin children's services efforts to improve wellbeing.

"Improved emotional health of primary school children can be understood in terms of happiness at school and at home, whereas for young people it will also involve reductions in the symptoms of adolescent anxiety and depression."

Describing the strategy as unique, the report adds: "Our commitment to support all children and not just those whose needs bring them to the attention of children's services goes beyond mere rhetoric.

"As far as can be ascertained, no other English local authority has based its children's services policies on such robust evidence about local needs or made such good use of data from around the world about what works."

Tony Howell, the council's strategic director for children and young people, said: "This has been not just the most thorough analysis of children's needs in Birmingham, but one of the most thorough analysis anywhere in the country."

Labour councillors feared the strategy would do little to drive up exam results or help children find jobs when they leave school.

Ian Ward, deputy leader of the Labour group, said that 29 secondary schools in Birmingham were failing to meet Government GCSE targets and were in danger of being closed or amalgamated.

Coun Ward (Lab Shard End) added: "Young people can't get decent jobs without qualifications in English and maths. They are the most important subjects and that's what we should be focusing on."

Councillor John Alden (Con Harborne) called for children aged 14 to be allowed one day a week off school in order to "go and find some work". This would allow them to "earn some self-respect and get a bit of cash".