The apology comes a decade after the conviction of nine men for sexual exploitation of children.

The case, which was turned into the BBC drama, Three Girls, became the most high-profile investigation of its kind, with the police admitting to victims on Tuesday: "GMP could and should have done much more to protect you and we let you down."

Chief Constable Stephen Watson QPM met and personally apologised to the three victims, who have also received "a substantial settlement of damages" from GMP.

He told them: "It is a matter of profound personal regret that your childhood was so cruelly impacted by the dreadful experiences which you endured."

Police are apologising 'to cover themselves'

One victim who received the apology, which was also delivered by letter, told Sky News: "I don't think they want to do the apology. I think they're just doing the apology just to cover themselves with the media."

In an exclusive interview, the victim, who we will call Sally, said: "I think the police just saw a bunch of girls who used to get arrested and thought we were a bunch of tearaways, just little b*****ds. They are going out with them [the older men], it's their problem."

The girls being groomed by a gang operating in Rochdale were often criminalised by authorities and were in and out of court.

Sally, who says she was abused by upwards of 150 men, said: "What my solicitor tried to explain was she's with men, a lot older than her. She's a child. Why are you not looking at these men? Why are you always prosecuting her?

"There were 86 arrests in two years. Now how can that not flag up like this child has been arrested 86 times in two years, she's been to prison, she's done every single order that's underneath the court? Why did they not look into it? And every time I gave a statement, I was always with a different Pakistani man, twice my age. They were never arrested, never questioned."

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Rochdale child sex victim comes 'face to face' with abuser

There was similar blindness to the problem in other services. When Sally got pregnant, aged 14, she says the local sexual health clinic knew, adding: "They wouldn't say it was wrong, the only thing they said to me was 'they're not going to marry you'."

Apology has come '10 years too late'

Maggie Oliver, a police officer who lifted the lid on the investigation and is now a prominent campaigner, said the apology "has come 10 years too late".

She told Sky News: "They have treated the victims with contempt. They have ignored every reasonable request just to apologise. They have made those girls fight every single step of the way.

"They would not engage. They overran every single legal time limit that is in place. They feel they are above the law, and actually, they really are in many respects."

In 2008, a police investigation was launched into allegations of child sexual abuse and one victim underwent hours of interviews about how she was systematically abused and raped by a group of men. She also provided DNA evidence.

It became clear that there were other potential victims, but with the police under pressure to hit targets in other areas, the allegations were not taken seriously enough.

Often the potential victims were arrested for committing minor crimes such as being drunk and disorderly, rather than police focusing on the men who were getting them drunk and raping them.

The 11-month investigation ended with the Crown Prosecution Service deciding the interviewed victim was "not credible".

The abuse continued until a new investigation, Operation Span, was launched in 2010. Eventually, Nazir Afzal, the newly appointed chief crown prosecutor for the North West, reversed the decision and the subsequent trial led to the conviction of nine men in May 2012.

Ms Oliver, an investigating officer at the time, said the police went for easier convictions with lower sentences and only focused on two victims, downplaying the scale of the abuse.

She said: "That case was not successful. A man who got a 13-year-old child pregnant, and had a foetus, was out of prison in less than two years.

"He should have been charged with rape. We knew he was the father of that unborn child. I believe the authorities took the easy road with the Rochdale case. Those men should be in prison for years."

Sally was only used as a witness in the case rather than a victim.

She said: "They said they recognised me as a victim but because they were helping 'Girl A' with her trial they needed me to be a witness. I'd say 'I know that guy and this is what happened to me' and they would say 'shut the f*** up it's not about you.

"I kept apologising but then I was thinking, 'Why am I apologising for telling an officer that I was raped as a child?'"

Sally's case was never taken up. After being a witness at the trial, she said, she was intimidated by her abusers. Her house was broken into and the word "slag" was written on her walls. She said that too was not properly investigated.

The letter from GMP says the crime "appears to have been filed without a proper investigation having been carried out. I am sorry that I can provide no adequate explanation for the closure of that crime."

Sally says the impact on her life has been immense.

"I've had no counselling. I've had no support. I wanted to do social work," she said.

"And I was really, really embarrassed when I got told that I can't continue with the course because I couldn't go onto the placement because my DBS came back that I had criminal convictions.

"I've been diagnosed with CPTSD, which is a complex post-traumatic stress disorder. I started hallucinating, I started hearing things and I started hearing people banging on me door. I was constantly telling the kids 'go and get the door, go and get the door.'

"Then at night time, I used to hear things banging in my bath.

"I'd grab my kids and then my kids would be like 'mum, there's nothing there'. I'd just lie in my bedroom all day, I wouldn't turn the telly on, I wouldn't open the blinds, wouldn't open the curtains. I wouldn't bath, I wouldn't brush my hair. I've ended up spending £1,000 on dental treatment because I wouldn't brush my teeth."

Kate Ellis, a solicitor at the Centre for Women's Justice who acted for the three claimants, said: "We hope that today's outcome will serve as a reminder to Greater Manchester Police, and other police forces, that they will be held to account if they fail to protect vulnerable children from exploitation and abuse."

Police say lessons have been learned from the Rochdale case, but victims and campaigners say the jury is still out.