UPDATED 1.21PM: The GCSB is just an antenna for the NSA in Maryland, according to one expert. 

Fresh documents reveal how New Zealand collects communications from diplomatic phones and computers in Asian and South American nations, including India, China, and Japan. 

The documents, obtained by NSA whistleblower Edward Snowden and shared with the New Zealand Herald, highlight discrepancies between secret and official foreign policy adopted by New Zealand.

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Otago University associate professor of information science, Hank Wolfe, says the analysis of the communications is almost certainly done in the United States.

"They have all kinds of specialised software, expensive specialised software, to analyse any kind of communications traffic."

Wolfe says the GCSB probably doesn't know what it's collecting, sending it away in bulk to the US.

He says a cellphone call is essentially a radio signal.

"The mechanics and physics of it are really simple. If you send out a radio wave it's in the ether. Anybody can pick it up with an antenna."

Michael Powles was once New Zealand's Ambassador to China and is anything but astonished at the spying revelations 

"Other people do, we do it. I don't think there's anything very startling about it at all."

Powles says it's very different from the GCSB's spying in the Pacific, where diplomatic relations are based on trust.

Read the New Zealand Herald's full report here

Read The Intercept's report here