New Zealand does not have a "realistic option of doing nothing" in the fight against Isis, Prime Minister John Key says, in advance of a Cabinet meeting to decide on whether to send New Zealand troops to Iraq to join forces against the Islamic terror group.

Cabinet will meet today to decide on the controversial issue, one which has split Parliament, with even some of Mr Key's allies vehemently opposed to intervening in the Middle East.

The Prime Minister has become increasingly vocal about his belief of the nation's need to intervene, and today said he didn't believe doing nothing was a realistic option.

Speaking on NewstalkZB this morning, Mr Key said he believed the public were "by a majority in favour" of deploying troops to join the fight, because of the increasing brutality of Isis' violent actions.

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"Obviously there are a number of people opposed, so it's not a slam dunk, but every poll I've ever seen ... show a majority in favour," he said.

"I think what the public are responding to, is they're saying the same thing I'm saying, 'Well these people are grotesque and they're brutal', and we really, I don't think, have a realistic option of saying [and] doing nothing. So the question becomes, 'Ok, well what do you do' because 60 countries are doing something.

"I think also New Zealanders are prolific travellers, these guys are using the internet to tap into people locally, we travel in the region, we've more often than not been the victims, unfortunately, in previous terrorist attacks, so I think people can understand what's going on."

Cabinet had "a lot to consider", but "for the most part" the complexities around the issue had been sorted out.

"There are some very, very minor things, I think, to tidy up, but for the most part I think we've got the answers we need."

If Cabinet votes in favour of sending troops to Iraq, there was "a risk" lives could be lost, Mr Key acknowledged.

"On the basis that if we were to send people, I think you have to accept it's a high risk environment, so there is a risk [that lives will be lost], I don't think you can say that there's absolutely no risk.

"But on the other side of the coin, I think the way to look at that is, 'do we run the risk of losing lives of New Zealanders on the basis that Isis becomes stronger?' and the answer, I believe, to that is 'yes'."

Mr Key said any decision on whether to send the New Zealand Defence Force to the Middle East would not be announced until tomorrow. He would not be drawn on possible dates for deployment of troops, or a possible return date, if Cabinet does give the green light.