Justin Bieber's manager Scooter Braun has warned the troubled pop star to change his ways or quit music for good.

The singer's bad boy behaviour has spiralled out of control in recent weeks and culminated in his arrest in Florida last week (ends26Jan14) on suspicion of driving under the influence, resisting arrest without violence and driving without a valid licence.

Bieber's legal troubles took a turn for the worse on Wednesday (29Jan14) when he was charged with assault after turning himself in to police in Toronto, Canada over an alleged spat with a limousine driver last month (Dec13).

It has now emerged Bieber's manager Braun has told the star the only way to continue with his music career is to make some serious changes or walk away from showbusiness.

In a new interview with Britain's GQ magazine, he says, "My responsibility is to always be there when they fall, always be there to help them get back up. But at some point I need to let them fail, because if they don't they're going to have no humanity... Sometimes he doesn't help himself because he's so angry... But no one really understands what he's living (through), only him....

"I can't baby him... I can say there is only one way around this, either we quit and let you try and find a normal life or you realise that this is what this is and we've got to keep fighting.

"And you're going to hate me some days because I'm going to say you can't throw a punch. You want to go out there and you want to bash their heads in... But the only way you're going to win them over is by being better."

Braun also opens up about an incident in Brazil, when a model took pictures of Bieber sleeping after a night out and shared them with the world, revealing the singer was upset about the damage to his reputation.

He adds, "He (Bieber) said 'I had a woman film me while I was sleeping, who I've never met before... She was in the house and she filmed me... They are assuming I slept with her and she was a prostitute... I've got to deal with that. I'm 19 (and) every single day I've got to deal with stuff like that. People thinking I had a baby or thinking I spit on my fans, just assuming the absolute worst about me."'