Watch out! Your smartphone can be hacked by world governments intent on spying on you, warns Edward Snowden.

The spy agencies of the US and UK governments are able to take control of your smartphone secretly by means of sending it a hidden text message, he says.

The former intelligence worker and whistleblower told the BBC on 5 October that Britain's security agency GCHQ has access to this sophisticated technology which has been provided by the American National Security Agency. The US uses such a programme to keep tabs on people in a project alleged to cost $ 1 billion. 

"[They send] a specially crafted message that's texted to your number like any other text message, but when it arrives at your phone it's hidden from you," Snowden told the BBC. "It doesn't display. You paid for it but whoever controls the software owns the phone." The message is designed to read the messages on the phone, check its web history, take photos with the camera and more, all without the user's knowledge.

This collection of spying tools is called the "Smurf Suite". According to Quartz, it consists of:

  • "Dreamy Smurf," a power management tool that turns your phone on and off without knowing.
  • "Tracker Smurf," a geo-location tool that allows the agency to follow you with a "greater precision" than what cellphone tower triangulation allows.
  • "Nosey Smurf," a listening tool that lets the agency hear through the microphone, even if the phone is off.
  • "Paranoid Smurf," a self-protection tool that makes it difficult for any user or technician to realize the phone has been hacked.

Neither the US government nor the UK government has commented on Snowden's claim.

Snowden, who has been living in Russia after blowing the whistle on a range of 'illegal' spying activities by the US government on common citizens in the name of tracking criminals like pedophiles and terrorists, also said in his interview to BBC that he was willing to go to prison as part of a deal with the US government that would see him able to return to his home country.

Snowden said that "of course" he was ready to spend time in prison in exchange for a return to the US, according to the Guardian. He told the interviewer that, in fact, he himself had "volunteered" to submit to a jail sentence.

"I've volunteered to go to prison with the government many times," he said. "What I won't do is I won't serve as a deterrent to people trying to do the right thing in difficult situations."