A "significant part" of the sexual exploitation committed against young girls in Rochdale should have been predicted and prevented, a serious case review has found.
Five of six victims on whom the report focused were "clearly in need of early help and at times intervention" by safeguarding agencies for several years before they were abused.
But there was no properly co-ordinated package of support and assessment which recognised such risks as neglect, domestic violence, parental health problems and substance misuse.
The report commissioned by Rochdale Borough Safeguarding Children Board (RBSCB) added: "Given the highly organised, determined and manipulative behaviour of the perpetrators, it would be unrealistic to imagine that their behaviour could have been predicted and that all harm to all the young people they abused could have been prevented.
"However, had the sexual exploitation been recognised and responded to at the earliest stages, these young people may have been protected from repeat victimisation and other young people may also have been protected from becoming victims."
The publication of the review comes more than 18 months after nine Asian men were convicted of the systematic grooming and sexual abuse of white girls in Heywood and Rochdale in 2008 and 2009.
The trial resulted in a national debate over the role of gangs of largely Pakistani-heritage men in grooming white girls.
A chance to stop the gang was missed in 2008 and both the police and the Crown Prosecution Service were forced to apologise for their failings.
An interim report to the RBSCB last year found that vulnerable girls, some as young as 10, who were being targeted for sexual abuse, being written off by those in authority who believed they were "making their own choices" and "engaging in consensual sexual activity".
The latest report covered the period from the beginning of 2007 up until 2012 and looked at the involvement of various agencies including social services, healthcare teams, the Crown Prosecution Service and Greater Manchester Police.
Report author Sian Griffiths, an independent social worker, said: "What has been identified throughout this review is a repeating theme of factors which impacted on the quality of practice in particular including:
:: Policy and procedures either not available or poorly understood and implemented at the front line;
:: Absence of high-quality supervision, challenge and line management oversight;
:: Resource pressures and high workload in key agencies, including CSC (Children's Social Care) safeguarding teams, A&E and police, contributing to disorganisation and at times a sense of helplessness;
:: Policies, culture and attitudes within many agencies which were actively unhelpful when working with adolescents."
Ms Griffiths adds: "What is indisputable is that the repeating nature of these failures exposes fundamental problems and obstacles at a strategic level in Rochdale, not simply in relation to individual practice.
"That the failings took place over a period of five years in relation to six young people who were in contact with at least 17 different agencies makes it absolutely clear that the problems were much more deep rooted than can be explained as failings at an individual level.
"It is also important to note that the experiences of these six young people whilst fundamentally important in their own right are accepted by agencies within Rochdale as being indicative of the experience of other young people at the time.
"What resulted represents a culture and a pattern of leadership that individuals were either unwilling or unable to change."
She said the key issues which led to the failures were:
:: Long-standing failings in leadership and direction at the most senior levels of key agencies;
:: Long-standing difficulties in achieving effective multi-agency working at the most senior levels reflected in operational practice;
:: Failure by strategic managers to focus on routine safeguarding practice, to understand how it was delivered.
:: Lack of an evaluative culture focused on the experience of young people, outcomes and the effectiveness of interventions.
:: Under-resourcing resulting in high workloads, decision making influenced significantly on managing budgets to the detriment of practice which would meet children's needs.
The report said that prior to and during the course of the review a number of internal proceedings have been taken against CSC managers and frontline practioners.
Some had been subjected to disciplinary action - although no-one is thought to have been sacked - while others have been referred to the Health and Care Professions Council, the regulatory body for social workers.
Greater Manchester Police's Chief Constable Sir Peter Fahy said he was not considering his position as a result of the report.
Sir Peter said the report had failed to confront a "fundamental" problem faced by police officers, who may investigate complaints from victims of sexual abuse only to find prosecutors will not take the case forward because of the unreliability of the key witness.
He warned of a "culture of hopelessness" among officers who are repeatedly asked to track down and return young people missing from children's homes, only for them to run away again.
Sir Peter told BBC Radio 4's Today programme: "Obviously the report says a huge number of things went wrong.
"What we have got here is a real difficulty, where we have got adolescents with very chaotic, disrupted childhoods, we have got police officers receiving and investigating complaints, but when they go to the Crown Prosecution Service and the wider criminal justice system, they decide that because they have got previous convictions and there are inconsistencies in their stories, they are not reliable.
"It creates a culture of hopelessness, where the police officers think 'what's the point?' I remember going to Rochdale and talking to the detectives who fundamentally believed the victim but were struggling because the victim had perhaps changed the story or gone back to the abuser and the court system had decided that this type of victim was unreliable as a class."
Greater Manchester's Police and Crime Commissioner Tony Lloyd has set up an independent commission to look into the handling of cases involving teenagers with chaotic lifestyles and reconsider the structures currently in place to protect them, said Sir Peter.
"Most people would say it is crazy that there are 17 or 18 different agencies in a place like Rochdale in charge of children," he said. "That can't make sense."
Sir Peter warned against viewing the Rochdale case as a race issue.
"I think there is a real danger that if we try to see this as a racial issue - which we don't believe it was - it then means society is not confronting some of these really difficult issues," he said.
Asked if he was considering his position in the light of the report, Sir Peter replied: "No."
He added: "There are still some major problems in the system. Tonight in Greater Manchester and across the country, police officers will be battling (with the question) 'What do I do with this 14-year-old person who keeps going missing? What's the point of taking them back to the children's home when they are going to run away again?'
"We haven't sorted out a solution to these really complex issues about young people."
Victim Support chief executive Javed Khan said: "It is utterly unacceptable that, instead of protecting these vulnerable young victims from sexual exploitation, the authorities judged, blamed and disbelieved them and their families and in doing so exposed these victims to further abuse.
"These young girls, who had been groomed by a group of criminals, were made to feel their suffering was their own fault when this was clearly not the case.
"It is to their great credit that they were later able to find the courage to give the evidence against their abusers which secured convictions in a number of cases.
"Cases like this remind us how important it is that the criminal justice system focuses on the needs of victims to ensure they are protected and supported and able to support successful prosecutions.
"Lessons must be learnt from this report and measures implemented to ensure no other vulnerable children are treated as at fault.
"Everyone has a responsibility to safeguard children and young people and report any concerns about abuse."
Anne Longfield, chief executive of charity 4Children said: "This damning, shocking report highlights just how badly these young, vulnerable girls were let down by a system that failed to protect and look after them.
"All of these children were highly vulnerable, with several placed into the care of the local authority for protection. Yet they were consistently turned away and written off when they were most in need, by organisations and professionals who were there to help.
"Child exploitation is a serious crime, which damages and destroys the lives of the most vulnerable children in our communities. We sincerely hope that this review results in child exploitation being prioritised and acted upon much more vigorously by everyone.
"We need a system which sets sights high for vulnerable children and which expects and enables all professionals to work together to co-ordinate determined meaningful action in response. Only then can we stand a chance of offering all of our children the safe and secure future that they deserve."
The College of Social Work chief executive Annie Hudson said: "These serious case review reports demonstrate the imperative of all agencies working together to identify and respond sensitively to the significant and profound needs of the young people subject to sexual exploitation and abuse.
"There is now greater public and professional awareness of the prevalence and corrosiveness of sexual exploitation, but there is much more that all agencies must do.
"Social workers and other professionals must be skilled in recognising the many different signs of sexual exploitation and abuse. They need to be able to build sustained and trusting relationships so that young people feel safe when talking about what is happening in their lives.
"All areas need to have well resourced and well led multi-agency partnerships that focus on building trust with young people, taking seriously concerns about child sexual exploitation and taking the right actions to protect and support young people.
"We need to find better ways of providing long-term support to young people in order to break cycles of distrust in adults, fearfulness and running away behaviours. Taking strong and effective action against perpetrators is also critical.
"The College of Social Work is committed to working with other national bodies to develop the knowledge and skills for best practice in this complex and challenging area."