"They want to own your phone instead of you," the whistle-blower said in an interview with the BBC`s Panorama program, referring to Britain`s Government Communications Headquarters (GCHQ) agency.
Snowden claimed that GCHQ used a series of interception tools called "Smurf Suite", after the blue cartoon characters, The Smurfs.
"Nosey Smurf" enabled spies to switch on a smartphone`s microphone even if the phone was off, he claimed.
Other programs used by GCHQ were nicknamed "Tracker Smurf" and "Dreamy Smurf", which allows phones to be switched on and off remotely, Snowden said.
He said the text message sent by GCHQ to gain access to the phone would not be noticed by its owner.
"It`s called an `exploit`," he said.
"When it arrives at your phone it`s hidden from you. It doesn`t display. You paid for it but whoever controls the software owns the phone," he added.
UK spies can hack smartphones: Edward Snowden
06 October 2015
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British spies can hack into phones remotely with a simple text message and make audio recordings or take photos without owners knowing, former US intelligence contractor Edward Snowden said.
