'I was a spy for the US': Edward Snowden hits back at critics in first American television interview

NSA whisteblower says critics are trying to 'distract' the public by discrediting his qualifications and professional expertise

NSA whistleblower Edward Snowden has claimed he was trained as a spy and worked undercover for US government agencies.

In his first US television interview from Moscow, the 30-year-old hit back at critics who claimed he was a mere low level analyst at the National Security Agency and questioned his expertise, arguing that they are trying to "distract" the public and discredit him.

Describing himself as a "technical expert", Snowden insisted he was trained as a spy by US authorities, lived and worked undercover and was assigned a new name.

"What I do is to put systems to work for the United States," he told NBC's Nightly News. "And, I've done that at all levels from the bottom on the ground all the way to the top."

He added: "Now, the government might deny these things. They might frame it in certain ways, and say: 'Oh, well, you know, he's a low-level analyst'.

"But what they're trying to do is they're trying to use one position that I've had in a career, here or there, to distract from the totality of my experience."

Snowden, wanted on espionage charges in the US, said he had worked for government agencies overseas, including the CIA and the NSA, and also lectured at the Joint Counterintelligence Training Academy.

He said his job consisted on developing sources and methods to keep information and people "secure in the most hostile and dangerous environments" in the world.

"So when they say I'm a low-level systems administrator, that I don't know what I'm talking about, I'd say it's somewhat misleading," he added.

Snowden fled to Hong Kong last year, and later Russia where he was granted temporary asylum, after he leaked classified documents which revealed details of the NSA's secret programme of phone and internet mass surveillance.

He was charged by US authorities with government property theft, unauthorised communication of national defence information and willful communication of classified communications intelligence information.

The full interview will air tonight on NBC