A major review into cases of sexual exploitation in Newcastle says there is an "urgent need" for the government to commission research into the "cultural values and attitudes" of perpetrators.
The majority of those convicted of abusing girls and vulnerable women in the city as part of Northumbria Police's large-scale Operation Sanctuary have been men of Asian heritage.
The government has said it will "look carefully" at the recommendations made.
The serious case review criticised the approach of authorities in Newcastle before 2014, but praised their response once several victims came forward, and the scale of the problem became clear.
Around 700 victims of sexual exploitation have been identified across the larger Northumbria Police force area - 108 in Newcastle. However, the report said some workers believed the cases identified so far reflect only the "tip of the iceberg", and warned that sexual exploitation is "still happening in Newcastle and other cities."
The report found:
Before 2014 "perpetrators were not consistently investigated, disrupted and prosecuted"
From 2014 "the interagency response was swift, determined and committed"
"Unlike some other areas, Newcastle agencies did not try and sweep this under the carpet"
The independent review said Northumbria Police's controversial move to pay a convicted child rapist nearly £10,000 to act as an informant in their investigation was not part of its scope. It did comment though that "appropriate procedures were undergone" and the tactic "sent a message to perpetrators that people will inform against them."
In early 2014, two women came forward to talk about the abuse they and many other victims had suffered. The review found a "stark contrast between the approach" taken by Newcastle City Council, the police and other agencies before and after that point.
The report said the scale of sexual exploitation in the city was previously "not fully understood" and an assessment made by authorities in 2013 found it was "not a significant problem in Newcastle."
It said there was a "lack of criminal investigation and prosecution of perpetrators" because officers were too reliant on victims to complain, which was often unrealistic, and not confident they could secure convictions. The report said, for example, "explanations were accepted, even when a young girl was found in the bedroom of an older man."
The report said failings in the authorities’ actions before 2014 “sent an unhelpful message to perpetrators - they were unlikely to be prosecuted or prevented from continuing to abuse - encouraging an arrogant persistence. It also had a significant impact on victims who learnt that nothing would be done against perpetrators.”
The report concluded "it is impossible to know whether... the focus of investigating, disrupting and prosecuting perpetrators might have occurred earlier."
Other high-profile cases of sexual exploitation, such as in Rotherham, have seen allegations of a cover-up of what was happening. In Newcastle, today's review found there had been no evidence of a lack of response, or a lack of concern, or fears around being seen as racist by investigating the issue. It said there was "no evidence of impropriety by any person in a position of authority."
However, it is believed that "over a period of years some perpetrators had abused hundreds of victims". Many victims have experienced long-lasting impacts on their lives, and some had abortions after being sexually exploited.
The report said perpetrators were "calculated and persistent", and committed "horrific acts of abuse, violence and manipulation, targeting and grooming the most vulnerable with a dismissive disregard for the criminal justice system."
From early 2014, when the prevalence of sexual exploitation in the city was better understood, the serious case review found there was "an immediate change of approach". That included disrupting and arresting perpetrators, raising public awareness of sexual exploitation, and setting up a special exploitation hub to support victims.
Newcastle has attracted national recognition for its services, and "become a centre of excellence and a source of expertise."
The report said a number of recommendations for improvements made during the review have already been implemented by authorities in the North East.
The report has also made a number of recommendations to the government.
Men from Pakistani, Bangladeshi, Indian, Iranian, Iraqi, Kurdish, Turkish, Albanian and Eastern European backgrounds have been convicted of abusing girls and vulnerable women in Newcastle.
The review said "information available about likely profiles of perpetrators and what drives their activities including the extent to which cultural values and attitudes are relevant is very limited. There is an urgent need for guidance to robustly address these issues."
The report also noted that Newcastle was notably different from other high-profile cases of sexual exploitation, because victims also included many vulnerable adults.
It said: "safeguarding vulnerable adults from sexual exploitation has not attracted the national profile of child sexual exploitation and lacks central guidance and advice."
The report recommended: "The Government should urgently issue guidance or advice on addressing sexual exploitation of vulnerable adults."
Other findings included:
Appearing as a witness in a criminal trial "continues to be an abusive and destructive experience for victims"
Current requirements around confidentiality in sexual health services makes identifying potential victims of sexual exploitation "extremely difficult"
The national compensation scheme for victims of violent crime "discriminates particularly unfairly" against victims of sexual exploitation who can be denied compensation because of involvement in other crimes that may be the result of the abuse they have experienced
If authorities do not recognise the sexual exploitation of children and vulnerable adults in their area "it is because they are not looking hard enough"