MELBOURNE • Australian police yesterday urged fans of Justin Bieber and their parents to stay vigilant on the Internet, after they filed charges for more than 900 child sex crimes against a 42-year-old man who impersonated the pop star online.

Bieber, a 23-year-old Canadian with more than 92 million followers on social network Twitter, who ranked among Forbes' most powerful celebrities from 2011 to 2013, is visiting Australia on his Purpose World Tour.

Queensland police had already charged the impostor with serious offences related to possession of child exploitation material, and use of the Internet and social media to groom those younger than 16.

But an examination of his computer led to the filing of an additional 931 charges against the man, who has not been named by police.

Police alleged the man used online platforms such as Facebook and Skype to communicate with victims and seek explicit images from young children, in offences dating from 2007. A lot of child exploitation material was found on his computer, police added.

"The fact that so many children could believe they were communicating with this particular celebrity highlights the need for a serious rethink about the way we educate our children about online safety," said Mr Jon Rouse, a member of a police task force to fight child exploitation online.

The incident highlights both the vulnerability of children using social media and communication applications, and the global reach and skill child sex offenders have in luring victims, added Mr Rouse in a statement.

A lawyer who represented the man in November last year, when his initial charges were filed, did not answer his telephone yesterday.

Bieber will be performing in Melbourne this week, before moving to Sydney and Brisbane next week.

REUTERS