A Tasmanian girl was instrumental in the arrest of a paedophile posing as Justin Bieber to have his victims stripped off in front of the computer for him. The girl had reportedly contacted the police. The police traced the impostor to his Middlesbrough home.

The Justin Bieber impostor is Robert Hunter, 35, whose ploy was to trick young boys and girls that he was the pop singer for the victims to send him their sexual videos and photos.

The police who handled the case discovered 800 videos from boys and girls as young as nine from across the UK, France, Spain, Italy, Serbia, Asia and Canada in the possession of Mr Hunter.

The victims interviewed by the police said that they believed Mr Hunter was Justin Bieber and were convinced to strip naked for him with the promise that he will be their boyfriend.

According to prosecutor Richard Bennett, boys were victimised by Mr Hunter after posing as a teenage girl and convincing them to perform sex acts on camera.

"He was able to persuade some of them that he was the music artist Justin Bieber and he encouraged them to perform sex acts on camera and he recorded many of them," Mr Bennett said.

Mr Hunter blackmailed all his victims if they refused to give in to his lewd desire.

A 12-year-old girl slashed her arms when Mr Hunter posted sexual photos of her on Facebook with her address and phone number.

Judge Peter Bowers said that this is the worst case of Internet sex abuse he handled.

''It's a warning to all parents of teenage children of what can be done via the internet. The public will be disgusted by how you have behaved even after you had been arrested and bailed. It represents callous, almost sadistic exploitation over a number of years preying on girls' naivety who were undermined by their own behaviour," Mr Bowers said.

Mr Hunter pleaded guilty to his crimes of inciting a child to engage in sexual activity.

Tina Pawson, mitigating lawyer for Mr Hunter described her client as "lonely individual who had difficulties in forming relationships with adults."

Ms Pawson said that Mr Hunter had shown repentance and welcomed his punishment openly.