The companies will prevent the government from accessing phone data—even with a warrant.
The FBI director criticized Apple and Google Thursday for adopting new policies that will block police from accessing private data on phones and tablet computers.
An FBI spokesman confirmed that Director James Comey told reporters he is "very concerned" that the new features could thwart critical police investigations. The bureau has contacted both companies to learn more, the spokesman said.
"What concerns me about this is companies marketing something expressly to allow people to hold themselves beyond the law," Comey said, according to the Associated Press. He reportedly said he fears a moment will come when "when people with tears in their eyes look at me and say, 'What do you mean you can't?'"
Last week, Apple announced that its new operating system will make it impossible for the company to unlock iPhones and iPads. Even if the police obtain a warrant, Apple would be unable to turn over information such as photos, video, or contact lists stored on the device. Google, which makes the popular Android operating system, announced a similar policy the following day.
"Unlike our competitors, Apple cannot bypass your passcode and therefore cannot access this data," Apple explained when it announced the new policy. "So it's not technically feasible for us to respond to government warrants for the extraction of this data from devices in their possession."
The company would still have to turn over data that users back up on the company's iCloud servers. Police could also obtain call records by contacting the telephone service provider.
Apple and Google did not respond to a request to comment on Comey's statements.
The FBI's director's criticism is the latest clash between law enforcement and technology companies in the wake of Edward Snowden's leaks about National Security Agency spying. Companies have been scrambling to upgrade their security measures to reassure customers that their private information is safe. But law enforcement officials fear the steps could empower criminals and hurt public safety.