The US has charged 72 suspected members of a sophisticated online child pornography ring that "incentivised" its members to engage in sexual acts with children and submit gruesome, violent material to build a massive private database that catered to pedophiles.

The crackdown is the result of a joint effort by the departments of Justice and Homeland Security launched in December 2009 to target about 500 people in 13 countries on five continents for their suspected participation in "Dreamboard," a members-only online bulletin board that was created to encourage the sharing of graphic images and videos.