Nearly 180 youngsters in care have not been allocated a social worker, which is one of the council's statutory responsibilities.

The department is now undergoing a "radical review" to address these major problems, with changes set to be introduced by the end of October.

Councillor MacLaren told the education, children and families committee that the city's vulnerable children must come first and the "sad history of mismanagement" must be reversed.

She said: "We have a system that is broken and it has been broken for a long while.

"That's what social workers said to me when I came into post, 'You have to change this'.

"It is a fact that at the moment we are not completely fulfilling our statutory responsibility.

"It's not fair for the 178 children who are in care not to have an allocated social worker. It is a piece of nonsense."

The council's priority is to ensure that it meets all of its statutory requirements, which include allocating a social worker to all children in care and on the Child Protection Register, reviewing children in care within set timescales and providing reports to the Children's Reporter within 20 days of a request being made.

Gillian Tee, director of education, children and families, said: "There is broad consensus that the current arrangements in relation to children's social work services need to change.

"Referrals are increasing markedly, there is difficulty meeting some statutory responsibilities and insufficient focus on preventative services for children and families.

"There is need for a radical review of how resources are used and how the service is organised."

She said the review was also designed to strengthen leadership, provide preventative family support for children at risk of being put into care or being excluded from school, and to ease staff workloads.

Twelve managerial positions will be lost through voluntary redundancy and redeployment.

But Green councillor Alison Johnstone said: "It's imperative that every child in our care does have a social worker and it is a grave concern to me that they don't. I'm not entirely convinced that this reorganisation is going to help that.

"We should be asking for more money instead of stretching the budget as far as it can go."