US charges 72 over global child porn operation
The US has charged 72 people it alleges were part of a global child pornography network used to share photos and videos of sexual abuse.
Announcing charges after 20 months of Operation Delego, senior US officials said some 600 users of a site known as "Dreamboard" had been investigated.
Attorney General Eric Holder said some images on the site showed the abuse of infants and young children.
The US has 43 of those charged in custody, with nine held overseas.
The 20 others charged as part of the US probe remain at large, Homeland Security Secretary Janet Napolitano said, and are known only by their internet pseudonyms.
Ms Napolitano described the amount of pornographic material seized as equivalent to 16,000 DVDs.
Authorities have arrested people in 13 other countries: Canada, Denmark, Ecuador, France, Germany, Hungary, Kenya, the Netherlands, the Philippines, Qatar, Serbia, Sweden and Switzerland.
Members of Dreamboard traded graphic images and videos of adults molesting children aged 12 and under, often violently, the US Department of Justice said.
Collectively the members of the site created a massive private library of images of child sexual abuse.
"The members of this criminal network shared a demented dream to create the pre-eminent online community for the promotion of child sexual exploitation," Mr Holder said.
"But for the children they victimised, this was nothing short of a nightmare."
Of the 52 individuals arrested under the US investigation, 13 have pleaded guilty, a justice department statement said, including two bulletin-board administrators in Canada and France.
Operation Delego represents the largest prosecution to date in the US of those who have participated in an "online bulletin board conceived and operated for the sole purpose of promoting child sexual abuse, disseminating child pornography and evading law enforcement", the statement said.
Dreamboard was created in 2008 and shut down in early 2011 when it became evident the US government had launched a probe into the online network.
The charges being handed to members of the website carry sentences ranging from 20 years to life in prison.