Police and councils are potentially downplaying the scale of child sexual exploitation by criminal gangs over concerns about negative publicity, a public inquiry has found.

Charities labelled the findings a “damning indictment” of responses to child exploitation across England and Wales, and called for urgent change to support and protect victims.

The Independent Inquiry into Child Sexual Abuse (IICSA) said there was “a flawed assumption” that child sexual exploitation was “on the wane”, with councils and police forces denying the scale of the problem, despite evidence to the contrary.

The report concluded this might be down to their determination to ensure they are not seen as “another Rochdale or Rotherham” – towns blighted by recent child sexual exploitation revelations – rather than a desire to “root out … and expose its scale”.

Prof Alexis Jay, who chaired the inquiry, said: “The sexual exploitation of children by networks is not a rare phenomenon confined to a small number of areas with high-profile criminal cases. We found extensive failures by local authorities and police forces in the ways in which they tackled this sexual abuse.”

The report detailed how child victims had reported being raped, abused and, in one case, forced to perform sexual acts on a group of 23 men while held at gunpoint.

They were often blamed by authorities for the ordeals while some even got criminal records for offences closely linked to their sexual exploitation.

Mark Russell, the chief executive of The Children’s Society charity, said the report was a “damning indictment” of responses to child exploitation.

“It is simply not good enough that many children who have suffered horrendous abuse are still being failed. How many wake-up calls will be needed?” he said. “It is desperately sad that children who report abuse are too often not taken seriously by professionals or made to feel they were complicit in their exploitation.”

Harriet Wistrich, the director of the Centre for Women’s Justice (CWJ) charity, which contributed to the investigation, said although welcome, the report had not engaged with the failure of the criminal justice system to prosecute these crimes.

“From CWJ’s point of view, the report is helpful in identifying the need to name and understand the problem properly which includes the proper collection of data. However, [it] represents a huge missed opportunity,” she said. “There is a lack of hard-hitting recommendations which will result in real change.”

The report, the 18th from the IICSA since it was established, featured testimony from more than 30 young witnesses across six case study areas – Bristol, Durham, St Helens, Swansea, Tower Hamlets and Warwickshire.

It said there was evidence of child sexual exploitation by networks in all six areas, but the relevant police forces were “generally not able to provide any evidence about these networks”.

Two areas – Swansea and Tower Hamlets – said there was no data to suggest there had been any child exploitation by gangs, despite evidence to the contrary.

The report concluded: “It was clear from the evidence that none of the police forces or local authorities in the case study areas in this investigation had an accurate understanding of networks sexually exploiting children in their area.”

There were also examples of victim-blaming, the report found, with children being described as “promiscuous” and “putting themselves at risk” in referrals to a support charity in St Helens. Similar language about victims’ behaviour was reflected across the inquiry.

Survivors, many of whom had a history of self-harm and running away from home, repeatedly described how their allegations against their perpetrators were routinely dismissed by police.

In one case, a girl abused from the age of 12 described how she was convicted of several offences including possession of a weapon after chasing her abuser with a bread knife after he assaulted her.

John O’Brien, the secretary to the inquiry, said the claim from some authorities that there was no evidence of child exploitation on their patch went down “badly” with the IISCA panel.

“It absolutely does require a culture shift. All organisations in this need to see the victim in this, not the crime,” he said.