The key to preventing child sexual exploitation is stopping young people who are "determined to put themselves at risk", from running away from care homes, the chief constable of Greater Manchester Police said.
Sir Peter Fahy insisted that the police had learned lessons after an investigation highlighted "significant failures" in the handling of widespread abuse in Rochdale.
The chief constable rejected calls from ex-detective Margaret Oliver for a full independent inquiry into the force's actions.
"The issue is that we still haven't solved the key issue behind CSE (child sexual exploitation) which is: how do you protect vulnerable young people who are determined unfortunately to put themselves at risk, that don't understand the degree to which they are making themselves vulnerable," he told BBC Radio 4's Today.
Asked if he saw the problem as being children putting themselves at risk, he went on: "Yes absolutely. Because of their upbringing, because of their difficult situation and because they are in care, every single day we have large numbers running away.
Police have admitted they failed to respond adequately to child sexual exploitation in Rochdale.
IPCC Commissioner James Dipple-Johnstone said:
There was a failure to recognise the seriousness and scale of what was happening in Rochdale.
It is appalling that young girls were being exploited and abused and the police did not handle it properly.
Greater Manchester Police has admitted that the focus in Rochdale was on tackling volume crime such as robbery and burglary.
The force simply did not recognise how to respond to child sexual exploitation on this scale.
An ex-detective said a report on police failures in the Rochdale child sex abuse scandal gave no new insights and that children in the area were still at risk.
Margaret Oliver said: "I know of men who have never been arrested, who are still walking the streets of Rochdale, who victims have named and accused of abusing them."
Oliver called for a full independent investigation of the kind carried out into similar problems in Rotherham.
"Virtually everything that is in that report today we were very well aware of in December 2010. The question that begs to be asked is why it has taken seven years to report that when that was widely known five years ago by all the officers working on Operation Span," she told the BBC Radio 4 Today programme.
"This was an opportunity, which has been missed again, to bring it all this out into the open. It is a nationwide problem and there is still an overwhelming desire to conceal the truth."
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