The National Security Agency chief said Monday intelligence services need access to encrypted devices to thwart terrorism, and hopes to find common ground with the tech sector on the issue.

Admiral Michael Rogers told a Washington cybersecurity forum that he does not believe Americans should be divided on the issue of encryption -- which makes it nearly impossible for outside parties to gain access, even in some cases with a warrant.

Rogers said that in the fight against terrorism, the concerns are the same as in law enforcement, and endorsed the view expressed by FBI director James Comey on gaining access to encrypted mobile devices.

Comey last year warned that law enforcement could be hampered in critical investigations after Apple and Google said they would encrypt their smartphones and give users the keys, making it impossible to hand over data even with a court order.

"Broadly, I share director Comey's concern," Rogers said.

"Most of the debate I've seen is that it's either all or nothing, that it's either total encryption or no encryption at all."

Rogers said it should be feasible to "come up with a legal framework that enables us within some quasi-process to address... valid concerns if I have indications to believe that this phone, that this path is being used for criminal, or in my case, foreign intelligence or national security issues."

The NSA chief called for the same kind of cooperation used to fight child pornography and exploitation, where tech firms report potential criminals to authorities.

"We have shown in other areas that through both technology and a legal framework and a social compact that we can take on tough issues, and I hope we can do the same thing here," he said.

The NSA has come under intense scrutiny both at home and abroad after former contractor Edward Snowden leaked documents about government surveillance programs that sweep up vast amounts of data from Internet and phone communications.

Rogers declined to comment on the latest reports from last week that the NSA implanted spyware on commercially made hard drives, and that it worked with British intelligence to hack into the world's biggest maker of SIM cards to be able to access mobile communications.

"We fully comply with the law," Rogers said. "We do that foreign intelligence mission operating within (a legal) framework."