The Conservative leader said he wanted "to understand what's gone wrong in these children's lives".

In a separate speech on Monday he also called for police to do more crime fighting and less form filling.

But Home Office Minister Tony McNulty dismissed the Tory leader's approach as "vacuous" and "wash-and-go politics".

Family breakdown

In a speech on social justice, Mr Cameron claimed teenagers who hide under hooded tops are trying to "blend in" rather than appear threatening.

Hooded tops - known as hoodies - have come to be viewed by some as a symbol of social disorder.

Earlier Mr Cameron told BBC Breakfast he was still tough on crime. "Of course people who commit crime should be held responsible.

Adult society's response to the hoodie shows how far we are from finding the long-term answers to put things right

David Cameron

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"But I think people want their politicians to ask the question: 'What is it that brought that young person to commit that crime at that time? What's the background to it, what are the long-term causes of crime?'

"If you're ill, it's no good putting a sticking plaster on it. You've got to get to the bottom of the illness.

"Let's try and understand what's gone wrong in these children's lives and we'll find it's about family breakdown, it's about drugs, it's about alcohol abuse, often it's young people who are brought up in care when they should be in loving homes.

"Let's now deal with those problems. That doesn't mean at the same we can't be tough when a crime is committed."

Pen pushers?

In his speech, he insisted: "We - the people in suits - often see hoodies as aggressive, the uniform of a rebel army of young gangsters.

"But hoodies are more defensive than offensive. They're a way to stay invisible in the street. In a dangerous environment the best thing to do is keep your head down, blend in."

It's a kind of wash-and-go approach to politics - get the headline, move on, never repeat the thing again

Tony McNulty

Cameron speech in full

In a separate speech on law and order, Mr Cameron urged police forces to show they were crime fighters, not just form fillers.

He argued chief constables needed greater freedom to fight crime and must also work to address areas where performance is lacking.

"The public doesn't want the police to give them learned lectures in sociology or criminology aimed at explaining why high levels of crime are inevitable or intractable or otherwise impossible to deal with," he said.

"They don't want agonised apologies and promises to get it right next time.

"They want the police to be crime fighters, not form writers. They want the police to be a force as well as a service."

'Headline grabber'?

But Labour has criticised Mr Cameron's line, calling it a "hug a hoodie" plan.

Mr McNulty also claimed the Conservatives had regularly voted against government plans to address anti-social behaviour.

"People have rights, of course, and we need to do all we can for them in that regard, but they also have responsibilities," he told the BBC.

"Sending out this hug-a-hoodie message just addresses one part of that, and it's for today's headlines.

"It's a kind of wash-and-go approach to politics - get the headline, move on, never repeat the thing again."

Former Tory leader Iain Duncan Smith, who is heading the new Conservative Social Justice Commission, said: "The conference today will show everybody that there's a huge and growing problem out there with a level of street culture that's violent, involved in drugs and getting worse.

"The biggest single root cause to most of this is the massive levels - highest in most of the western world - of family breakdown."