Dozens of children suspected of being groomed and abused by gangs of Asian men were failed by police and local authorities, a report has concluded.
Some victims subject to "profound abuse" told carers and police officers about the sexual assaults, giving names and addresses, but no action was taken, according to the report into child sexual exploitation in Manchester.
The 145-page report concluded: "The authorities knew that many were being subjected to the most profound abuse and exploitation but did not protect them from the perpetrators."
The report centres on Operation Augusta, set up in 2004, prompted by the death of Victoria, 15, a girl under the care of Manchester City Council, who reported being raped and injected with heroin by a 50-year-old Asian man.
She died of a drugs overdose two months later on September 29, 2003.
Joan Agoglia, Victoria's grandmother, broke down in tears at a press conference in Manchester with Mr Burnham, Ms Oliver, and the report's authors.
Mrs Agoglia said her granddaughter went into care against her wishes after her own daughter developed terminal brain cancer.
She added: "She was such a lovely girl, a wonderful girl. She didn't deserve to die. I've been fighting all my life for this. She told me herself what these men had done to her.
"I used to give her a bath because she was so bruised. I promised her...there's no way they are going to get away with this."
A new inquest into Victoria's death has been ordered by Andy Burnham.
The police operation identified at least 57 victims and 97 potential suspects, some involved with Victoria, and a "compelling picture of the systemic exploitation of looked after children in the care system" was established by detectives.
But senior officers at Greater Manchester Police (GMP) chose to under-resourced the investigation, the report said.
A decision was then made to close it down then communicated to senior officers of Manchester City Council at a meeting later that day on April 22, 2005.
Minutes of both meetings have disappeared, though one officer's note mentioned discussion of "press strategies" and several officials have chosen not to co-operate with the review.
In each case the report concludes repeatedly with the same sentence: "We cannot offer any assurance that this was appropriately addressed by either GMP or Manchester City Council."
As a result, "very few of the relevant perpetrators were brought to justice and neither were their activities disrupted".
This was despite "clear evidence" teenage girls, aged 12 to 16, were being sexually abused "generally perpetrated by a group of older Asian men" including the police having their names, where they lived and worked.
The report concludes it would be "wrong" to say Operation Augusta continuing would have "prevented further offending" but is "of concern" potential suspects have since been involved in grooming.
It calls on the mayor, police and council to consider how "the people who appeared to present a risk to children in 2004 can now be brought to justice and any risk they still present to children mitigated".
Mayor of Greater Manchester Andy Burnham ordered the 'assurance review' after the BBC street grooming documentary The Betrayed Girls was broadcast in 2017.
It featured Maggie Oliver, a former GMP detective turned whistleblower who worked on Operation Augusta.
She said there was a "deliberate and intentional desire to bury the truth" at GMP.
"This has been 15 years of my life, it has almost destroyed me, I've lost my job, I've lost my home, I've lost my health, Joan [Agoglia] has lost her granddaughter, all those children we knew were being abused were cast aside," Ms Oliver said.
"How many more children have those abusers abused in 15 years? It is unforgivable and this report makes me feel vindicated, it actually gives me a sense of closure."
The Greater Manchester Combined Authority have said that a new criminal investigation looking into the Victoria Agoglia's case and those involved in Operation Augusta has now been opened by GMP.
They said: "Whilst Victoria’s death was investigated at the time, allegations of long-standing sexual abuse that preceded her death have never been investigated and perpetrators not pursued."
GMP have apologised in a YouTube video, with Assistant Chief Constable Mabs Hussain saying that they accepted that "authorities fell short of doing all they could to protect and support the child victims identified in the report."
He said: "I would urge anyone who was involved in the original operation as a victim, potential victim or witness to please come forward and contact us, so that we and partner agencies can provide you with any support we can."
He added: "Greater Manchester Police will investigate any report of child exploitation that is made."
If you have been affected by this case and wish to speak to police, or if you believe you have information that can assist the investigation team, they can be contacted via firstname.lastname@example.org
If you have been affected by this case and would like to seek support from specialist agencies but do not wish to speak to police, then Victim Support can be contacted on 08081689024