CIA chief Brennan supports FBI in Apple encryption case

America's top spy said in an interview Wednesday that he supports the FBI's high-profile battle to force Apple to unlock an iPhone used by one of the San Bernardino attackers.

In a conversation with National Public Radio, Central Intelligence Agency Director John Brennan said the public would never accept criminals or terrorists having exclusive access to a physical storage box, and asked why an encrypted phone should be treated any differently.

"What would people say if a bank had a safe-deposit box, or a storage company had a storage bin, that individuals could use and access and store things, but the government was not going to be able to have any access to those environments?" Brennan asked.

"The FBI clearly has a legitimate basis to try to understand what is on a phone that is part of a very active investigation."

Apple is at the heart of a closely watched legal battle after a US judge ordered the tech giant to find a way to unlock the encrypted iPhone in question, which belonged to Syed Farook, a US citizen.

Along with his Pakistani wife Tashfeen Malik, Farook gunned down 14 people in the Californian city of San Bernardino in December.

Investigators want help hacking the device, and have demanded Apple's technical assistance in at least 10 other cases.

Facebook CEO Mark Zuckerberg has said he is "sympathetic" with Apple's quandary and other tech firms have offered guarded support.

Microsoft founder Bill Gates has straddled the issue, saying in a BBC interview that there should be a debate over whether governments "should be able to access information at all or should they be blind."

However, he disputed a report by the Financial Times that he "backed" the FBI in the Apple case. The newspaper later changed its headline to reflect Gates's subsequent comments.

Brennan was also asked more broadly about the general threat of terrorism.

He said that even though Al-Qaeda has been "neutered" in many regions, the global terror risk has grown considerably with the rise of the Islamic State group, whose targets seem to know few boundaries.

"It's seen as more of a threat (than Al-Qaeda,) not just to individuals, but also to economic and commercial and other types of interests globally," Brennan said.