The NZSIS spy agency has kept the National Terrorism Threat Level at low, meaning a terrorist attack remains a realistic possibility but they don't know of any specific credible plots.

In a statement, Director-General of Security Andrew Hampton says it's important to remember a low threat level does not mean an absence of threat.

"An attack remains a realistic possibility and there are individuals of concern being investigated by the NZSIS.

"The nature and amount of violent rhetoric shared online suggests there are people in New Zealand who may aspire to commit an attack, but we have not seen this translate to planned attempts to undertake a physical act of violent extremism."

He says the determination of a low threat level has followed a routine annual review, and is based on an assessment of classified and open source material by a multi-agency group that is then consulted on widely with New Zealand's national security agencies.

However, the threat level is continually evaluated and can change at any time.

The agency urges people who sees suspicious or concerning behaviour to report it to police on 105, or through the NZSIS website - and call 111 in an urgent or life-threatening situation.

University of Waikato law professor Al Gillespie says the threat level has stayed at low since November 2022, after it went up to high (highly likely) following the attacks on the Christchurch mosques, dropping to medium in April 2019.

"This is good news, especially as tensions rise around the world and other countries have been forced to revisit their terror threat levels in the wake of the Gaza/Israel conflict; and of late - the Red Sea and Houthi problems.

"All of these can have knock-on effects to domestic terror, but this is something we have not seen in NZ. It is also good as it would seem we are moving past some of the concerns that accompanied the Covid period."

He also offers a reminder of the risk that still exists at a low threat level.

"The biggest risk of all, is that surveillance only works on what you can see, as that which is near invisible can be near impossible to detect.

"But the SIS has been doing a lot of work, trying to encourage people to spot the sighs of concern, and report to the SIS suspicious activities - although not only with terrorism, also with espionage and foreign interference (of which they have also, recently, made some big calls about China)."

-RNZ.