A strategic studies specialist says if New Zealand spies did target the competitors of a government minister when he was bidding for a top trade job, it is arguably the most concerning spying revelation yet.
Journalist Nicky Hager says documents leaked by US whistleblower Edward Snowden show the GCSB spied on candidates vying to lead the World Trade Organisation (WTO) in a bid to help New Zealand's contender Tim Groser in 2013.
Victoria University Professor of Strategic Studies, Robert Ayson, said if the claim was correct, it raised questions for the public about the GCSB's role.
"I think it does push the boundaries a little bit. I think a lot of New Zealanders would expect that we would be collecting information on issues that relate more directly to national security.
"I'm not sure they would necessarily expect that when it came to a competition for a top trade organisation role that collection agencies would be involved," Professor Ayson said.
He said that, in the Tim Groser case, the alleged spying seems to be borderline.
"If those allegations are correct, based on those documents that have been released, then I think it's starting to become a bit of an issue for me.
"I mean, is that what we want to have an intelligence service for?"
Auckland University law professor and Trans Pacific Partnership opponent, Jane Kelsey, believes the GCSB had a dedicated team for spying on trade.
"Well, we suspect strongly that the Five Eyes (spy network), most of whom are involved in the Trans Pacific Partnership Agreement negotiations, have been keeping a close eye, not only on those of us who are non-government critics, but also possibly some of the governments in the negotiations."
United Future leader Peter Dunne suspects there was no ministerial warrant signed authorising the GCSB to spy for Tim Groser.
"I think this is far more likely to have been a case of the GCSB deciding off its own volition that this was a good idea," Mr Dunne said.
"And that, to my way of thinking, raises a far more serious question, I've been concerned for some time that they act too much on their own initiative and not enough at the direction of ministers.
"If this is what happened in this instance, then it's another example of where they overstepped the mark."
Trade Minister Tim Groser, in Korea yesterday signing a free trade deal, refused to provide any details about the GCSB's alleged spying on his behalf.
"If we were to start commenting on individual allegations the whole system would come out," Mr Groser said.
"We simply do not comment on individual issues concerning our external intelligence agencies."
Prime Minister John Key has also refused to elaborate on the Tim Groser spy claims, except to say that the advice he has received is that the GCSB's spying is lawful.