Edward Snowden has not been offered a plea deal by U.S. authorities, even though then-Attorney General Eric Holder said earlier this year the National Security Agency (NSA) leaker had "spurred a necessary debate" and that a deal was in the realm of the possible.

In an interview with BBC television, Snowden said he had offered to do time in prison as part of an agreement with prosecutors.

"We are still waiting for them to call us back," the 32 year old said, according to The Guardian -- the newspaper that had first published his revelations about the federal government's massive bulk collection of data.

But senior figures in American and allied security services are "unforgiving," and former NSA Director Michael Hayden went to far as to say he expected Snowden to "die in Moscow."

"He's not coming home," the retired four-star general added.

"I've volunteered to go to prison with the government many times," Snowden 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."

The former NSA contractor would be looking at a sentence of up to 30 years if he were to return to the United States without a plea deal -- and if he were convicted under the Espionage Act charges brought against him.

"So far, they've said they won't torture me, which is a start, I think," he said about his interactions with the U.S. government, according to Time magazine. "But we haven't gotten much further than that."

Amid reports the Obama administration is looking into methods to circumvent smartphone encryption, meanwhile, Snowden told the BBC users can do "very little" to prevent security services from getting "total control" of their devices.

"For example, if it's in your pocket, (the British intelligence agency GCHQ) can turn the microphone on and listen to everything that's going on around you -- even if your phone is switched off because they've got the other tools for turning it on," he said.