LONDON — A report led by the Great Manchester Police on Friday criticized its own officers for failing to recognize the scale of child sex abuse in a northern town and putting too much emphasis on the credibility of the victims.

The report looked into how officers handled the abuse scandal in Rochdale, where dozens of young girls were believed to be groomed and trafficked for sex by a network of men. Allegations of abuse were first reported in 2008, but it wasn’t until months later that police opened investigations.

Nine men of Pakistani and Afghan heritage were eventually jailed in 2012 for crimes including rape and trafficking. One victim was just 13.

Former detective Margaret Oliver, who had resigned to protest the handling of the scandal, said similar crimes are still continuing in Rochdale and elsewhere in Britain.

“It is a nationwide problem and there is still an overwhelming desire to conceal the truth,” she told the BBC. “This was an opportunity, which has been missed again, to bring all this out into the open.”

The Greater Manchester Police admitted the force was too distracted by tackling crimes like burglary to listen to abuse victims. But the report said no police officer would be disciplined.