The number of people on a Government watchlist has increased, Prime Minister John Key says.
In November, Mr Key revealed 30-40 people were on a watchlist because of their involvement with or support for Islamic State and a further 30-40 required further investigation.
Mr Key told Morning Report the group of people who were on the "unsure watchlist" had increased to 60-70.
He said the increased number would be a more significant factor for officials deciding the terrorist threat level than the deployment of soldiers to Iraq.
"There's a reason why the 35-40 people on the watchlist are there, and that's because we believe their, at least, desire in terms of actions they might take are more credible and more specific."
The level of security at Parliament had also changed since a threat on the life of an Australian senator and a terrorist attack on the Canadian parliament last year.
Last week, Mr Key announced 143 troops would be sent to Iraq to train local security forces.
Foreign deployment increase violence - Sooden
Meanwhile, a New Zealander held hostage in Iraq by Al Qaeda supporters for four months in 2005 says New Zealand should withdraw from the US-led coalition in Iraq.
Harmeet Sooden is heading back to the country to work with the humanitarian organisation Christian Peacekeeper Teams, and will be based in Iraqi Kurdistan, where he will help refugees.
He told Morning Report he was deeply concerned about the Government's decision to deploy defence forces to Iraq.
"As a New Zealander I feel responsible to some degree for my government's actions and I think, at least according to NGOs that this deployment, or at least this coalition is likely to increase the level of violence in the region."
Mr Sooden said US policies over the past few decades had had a devastating impact on Iraqi society.