Up to 20 British children are among more than 150 alleged victims of a man accused of posing as Justin Bieber to obtain explicit images from youngsters.

Gordon Chalmers, a university law lecturer from Brisbane, faces 931 sex offences dating back a decade, including rape and making child exploitation material.

The 42-year-old Australian is said to have used online platforms such as Facebook and Skype to impersonate the Canadian pop superstar and contact youngsters.

Police said Chalmers then enticed fans to send him explicit pictures.

Officers said the offences are believed to involve 151 alleged victims, including 50 from the United States.


Image: Gordon Chalmers is a university lecturer

Chalmers, who worked at Queensland University of Technology, was arrested in November after a tip-off from German and US authorities.

He has been charged with "a number of child sex offences" including grooming and possessing explicit material.

After a "thorough examination" of his computer, a large amount of material was seized and he was then charged with more than 900 further offences dating back to at least 2007.

The additional charges include rape, indecent treatment of children and making child exploitation material.

Chalmers is due to appear at Brisbane Magistrates' Court on 6 April.

Image: Pop superstar Bieber is currently on a world tour

Police are urging Bieber fans - known as "Beliebers" - and their parents to be vigilant when using the internet.

Detective Inspector Jon Rouse described the breadth of offences as "horrendous".

He said: "This investigation demonstrates both the vulnerability of children that are utilising social media and communication applications and the global reach and skill that child sex offenders have to groom and seduce victims.

"The fact that so many children could believe that they were communicating with this particular celebrity highlights the need for a serious rethink about the way that we as a society educate our children about online safety."

Bieber, 23, kicked off the Australian and New Zealand leg of his Purpose world tour on Monday.