DeLaune said NCMEC would educate tech companies and "hope they use creativity" to address the issue. Under pressure from regulators and lawmakers, Facebook has vowed to speed up removal of extremist and illicit material.The child grooming system evaluates factors such as how many people have blocked a particular user and whether that user quickly attempts to contact many children, Davis said.Facebook has not previously disclosed data on child nudity removals, though some would have been counted among the 21 million posts and comments it removed in the first quarter for sexual activity and adult nudity.The machine learning tool rolled out over the last year identifies images that contain both nudity and a child, allowing increased enforcement of Facebook’s ban on photos that show minors in a sexualized context.Facebook’s rules for years have banned even family photos of lightly clothed children uploaded with "good intentions," concerned about how others might abuse such images.Machine learning is imperfect, and news agencies and advertisers are among those that have complained this year about Facebook’s automated systems wrongly blocking their posts.

A similar system also disclosed on Wednesday catches users engaged in "grooming," or befriending minors for sexual exploitation. Weld Stud Nuts Manufacturers Facebook said that company moderators during the last quarter removed 8. Still, DeLaune acknowledged that a crucial blind spot is encrypted chat apps and secretive "dark web" sites where much of new child pornography originates.With the increase, NCMEC said it is working with Facebook to develop software to decide which tips to assess first.The company is exploring applying the same technology to its Instagram app. Davis said the child safety systems would make mistakes but users could appeal. It makes exceptions for art and history, such as the Pulitzer Prize-winning photo of a naked girl fleeing a Vietnam War napalm attack. Encryption of messages on Facebook-owned WhatsApp, for example, prevents machine learning from analyzing them.