One or two New Zealanders on a terror watchlist are considered so threatening that they are being monitored every minute of the day, Prime Minister John Key says.
But the main concern to the Government are the potential terrorists who are not on the radar of New Zealand's spy agencies, Mr Key told Radio New Zealand this morning.
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All of the 40 people on the watchlist were linked to, or "on the periphery" of the Islamic State (ISIS), and were likely to be regularly reading the extremist group's propaganda.
Mr Key said one or two of the people were "quite threatening individuals" and they were under 24-hour surveillance.
They were being watched both physically and electronically under new powers which were given to spy agencies a year ago.
These individuals wanted to commit attacks in New Zealand, Mr Key said, but were unlikely to do so.
"Their capacity to do a lot is limited," he said. "My concerns always are not the people that we know about, it's the ones that we don't know about, and that's what you [saw] in Paris," he told the radio station.
Others on the watchlist were raising money for ISIS, trying to get to Syria or Iraq to fight, or were already in the Middle East.
It is a criminal offence to fundraise or send money to terrorist groups.
Asked by Radio New Zealand why authorities did not take action against people who were sending money offshore, Mr Key said: "That's exactly the question I asked my officials: 'If you see someone that looks like they're planning some sort of activity, why can't you deal with it?'
"And the answer I always get from my agencies is that it's not as clear-cut when you get to court. They claim different things, and ... they just wanted absolutely firmer evidence to take them to court."
Since the Paris attacks, countries are looking to escalate their efforts to combat ISIS's threat.
The United Nations Security Council has unanimously voted to call on member countries to act against the terror group.
New Zealand has already deployed troops to Iraq to help train local forces.
Mr Key reiterated this morning that New Zealand's deployment would not be expanded.
He said a larger commitment would mean New Zealand risked getting stuck in Iraq "forever".