Assistant Chief Constable, Dawn Copley said: "I want to start by saying we openly acknowledge that mistakes were made and victims were let down.
"For our part in that we apologise to the victims and we give them our assurance that lessons have been learned, changes have been made and we are determined to use this to continue making improvements.
"This matter was referred to the IPCC in December 2010. They decided to supervise the investigation which was then conducted by our Professional Standards Branch
"The first investigation report was based on the findings of an internal review which had already taken place. The IPCC rightly challenged this and further investigation work was required. GMP then proposed amended terms of reference, which the IPCC approved and these have now been met in full.
"The investigation has examined the conduct and actions of 13 officers who were involved in Operation Span and the policing of Rochdale Division. These ranged from constables to the Divisional Commander.
"This report, and the previous SCR, identified that at the time in 2008-10 there was a strong target driven focus, predominantly on serious acquisitive crime. At best this was distracting for leaders and influenced the areas that resources were focussed on. This has now changed significantly. CSE remains a huge challenge for GMP but it is now one of our top priorities and our understanding and experience of dealing with these types of cases has increased significantly.
"It is unusual for internal investigation reports to be released into the public domain. However, we recognise the significant public interest in this case and felt it was important to take the unusual step to issue this report and to demonstrate to the public that this has been thoroughly investigated, addressed and lessons have been learned.
"IPCC supervision has ensured that all relevant investigation has taken place and they have agreed that the terms of reference have been addressed.
The IPCC also been fully aware of the sanctions and outcome for officers, which we agree are at the appropriate level."
A total of 7 officers were served with misconduct notices and were formally interviewed about their actions and decision-making, their handling of investigations and victim care. Many more officers were interviewed and all fully cooperated with the investigation.
The seven officers who were served notices include the former Divisional Chief Superintendent, a Superintendent, plus two Detective Chief lnspectors, two Detective lnspectors and one Sergeant. All received management action in respect of their performance with the exception of one Detective lnspector who the investigation found had a case to answer for misconduct. This officer retired prior to the completion of the investigation.
All officers have been spoken to, the investigation findings shared with them for their personal development and learning and the misconduct and performance issues have been individually addressed.
"Ultimately, despite the issues highlighted in this report, nine men were jailed for a total of more than 80 years for their part in the abuse and we should not lose sight of that.
"Huge developments have been made in child protection and there are many dedicated professional and volunteers involved across all agencies. In Rochdale, the multi-agency Sunrise team has made huge strides.
"In addition, Project Phoenix is a multi-agency response to CSE across the whole of Greater Manchester. This is made up of teams of police officers, children's services staff, health workers and other supportive professionals who have come together, using their collective expertise to safeguard vulnerable young people at risk of exploitation and relentlessly target those who would try to exploit them.
"Since 2010 we have had a number of CSE operations that have targeted offenders across the force, including Doublet which has so far seen us make bring 55 charges against 10 people.
"It is clear that mistakes were made in this investigation. We have, and continue to make significant improvements because of the lessons we have learned. We urge victims to come forward knowing that we will take them seriously and thoroughly investigate what has happened to them. People who abuse children will be traced and brought to justice."