Greater Manchester Police has admitted it "could have done more" to protect victims of child abuse but pursued crimes such as burglary and car theft instead due to enforced targets.
A former GMP detective has accused the force of a "lack of desire" to follow up on allegations of paedophile rings in Rochdale because such crimes are "difficult to prosecute".
GMP chief constable Sir Peter Fahy said some of his officers developed a "mindset" that the child victims were unreliable, which made them reluctant to fully investigate the allegations.
Fahy said the force was under "significant scrutiny" to improve its performances for offences such as burglary and car crime. He added the imposition of targets to drive performance led to "anomalies in behaviour" which meant investigations of sexual abuse of vulnerable children at children's homes in Rochdale "should have been better".
In 2012, nine members of a Rochdale paedophile gang were jailed for a total of 77 years after they were found guilty of sexual abusing girls as young as 13.
A report by the compiled by the Rochdale Borough Safeguarding Children Board (RBSCB) ruled the victims were raped, trafficked and plied with drugs for several years due to "missed opportunities" by police, social workers and the Crown Prosecution Service.
Former detective constable Margaret Oliver told ITV News she passed on allegations of abuse in Rochdale in an internal report to officers more than 10 years ago but they were not fully pursued.
She said: "There's no lack of evidence, the evidence is there, there is a lack of desire to follow the lines of enquiry.
"Peter Fahy is responsible for GMP. He cannot pretend that he doesn't know what is not being done in relation to the investigation of this kind of crime."
She added: "They were only interested in target crimes: robbery, burglary and car theft. Because this kind of crime is difficult to prosecute and didn't show up quickly on crime figures they weren't interested."
The claims from Oliver arrive following a damming report which revealed 1,400 children were abused for years in Rotherham due to a series of failings by authorities.
Fahy said the target driven policing was removed two years ago, and that the "unreliable victims" mindset had changed within the police force but remained in the courts.
He added: "Greater Manchester Police has recognised that it could have done more to support the victims of child sexual exploitation in Rochdale. There had already been major investigations of sexual abuse of vulnerable children at children's homes in Rochdale, but it is now clear that our response should have been better. The response in Rochdale has been subject to external investigation and review.
"Since 2010 we have moved considerable resources into child protection and the investigation of sexual exploitation.
"There have already been a number of major investigations across Greater Manchester relating to sexual abuse of children, including historic cases, which have led to convictions. These are complex and challenging investigations and we are committed to bringing offenders to justice.
"As has been identified nationally, the imposition of targets to drive performance inevitably leads to anomalies in behaviour. Two years ago, with the support of the Police and Crime Commissioner, GMP removed these targets and has been encouraging officers to do what is right for victims."