The Prime Minister is being accused of threatening the safety of four SAS logistics officers in Afghanistan to gather intelligence, by speaking publicly about the operation.
John Key has told the media the non-combat officers are there to build a case on insurgents responsible for the death of five New Zealand soldiers last month.
He says information will be handed over to the United States Military's special forces, so they can find those responsible for the killings.
The Labour Party's former Defence Minister, Phil Goff, says the prime minister has tipped off the intelligence officers' Taliban enemies and threatened the security of all New Zealand soldiers serving there.
"By big-noting in the way that he has, the Prime Minister has effectively put in jeopardy the lives of the four New Zealanders that he sent up there. That would never have happened in the past; I can't understand why he would have made a comment like that in advance of any operation."
However, a defence analyst, Jim Veitch, says the Taliban will already be aware of the situation.
And he says the intelligence mission is also about preparing for the safe withdrawal of all New Zealand soldiers next year.