The revelation of a domestic terrorist threat in New Zealand has raised alarming questions, a security analyst says.
The National Security System Handbook, released by the Prime Minister's department, refers to the threat - but gives no further details.
And the annual report of the Inspector-General of Security and Intelligence has confirmed the SIS responded to a suspected terrorist act in the second half of last year.
Paul Buchanan of geopolitical consultancy 36th Parallel Assessments said it appeared no one had been arrested or charged in relation to the domestic terrorist threat.
"If that is the case was it thwarted so early that the authorities were not able to gather evidence that they could present to the court, and if that is the case, where are the suspects now?"
Mr Buchanan said it had to be asked why New Zealand's national terrorist threat level was not raised from low to either moderate or medium.
The National Security System is New Zealand's highest-level response to the most serious threats against the country.