US attorney general Eric Holder said on Tuesday he was worried that attempts by technology companies to increase privacy protections were thwarting attempts to crack down on child exploitation.

Speaking at the biannual Global Alliance Conference Against Child Sexual Abuse Online in Washington, Holder warned that encryption and other privacy technologies are being used by sexual predators to create “more opportunities to entice trusting minors to share explicit images of themselves.”

“Recent technological advances have the potential to greatly embolden online criminals, providing new methods for abusers to avoid detection,” he said. “When a child is in danger, law enforcement needs to be able to take every legally available step to quickly find and protect the child and to stop those that abuse children. It is worrisome to see companies thwarting our ability to do so.”

Holder said perpetrators were using cloud storage to store “tens of thousands of images and videos outside of any home or business – and to access those files from anywhere in the world. Many take advantage of encryption and anonymizing technology to conceal contraband materials and disguise their locations.”

His comments come as Apple, Google and others have sought to increase the use of encryption in the wakes of the Guardian and Washington Post’s disclosure of the National Security Agency’s (NSA) massive domestic spying operations.

Last week FBI director James Comey expressed similar concerns after Apple disclosed it would not be technically feasible for law enforcement to unlock encrypted iPhones and iPads because the devices would no longer allow user passcodes to be bypassed.

All the major tech firms are now working on giving customers’ greater control of their information. Apple’s move came shortly before Google, DropBox and others announced the launch of Simply Secure, a group that aims to make encryption and other privacy tools more readily available in consumer-friendly formats.

“I am a huge believer in the rule of law, but I also believe that no one in this country is beyond the law,” Comey told reporters at FBI headquarters in Washington. “What concerns me about this is companies marketing something expressly to allow people to place themselves beyond the law.”

Holder said that in the two years since the launch of the Global Alliance Against Child Sexual Abuse Online more than 50 countries had joined this initiative and the US had taken action against 5,000 criminals within the US dedicated to the “sexual abuse of children and the use of online networking platforms to traffic in child [abuse images].”

He said steps were being taken to educate children in order to eradicate their exploitation online and investigators were embracing “revolutionary technological tools in many aspects of this effort, from prevention through interdiction.” The Justice Department is “stepping up our efforts to build strong partnerships with technology companies, which can be important allies in this fight,” said Holder.

In the future law enforcements’ relationships with the tech companies will “only become more critical to making the internet a safer space for children around the world,” said Holder. “Moreover, we would hope that technology companies would be willing to work with us to ensure that law enforcement retains the ability, with court-authorization, to lawfully obtain information in the course of an investigation, such as catching kidnappers and sexual predators. It is fully possible to permit law enforcement to do its job while still adequately protecting personal privacy,” he said.