Prime Minister John Key said it was regrettable that two New Zealanders involved in conflict in Afghanistan were injured by friendly fire last year.
Such incidents happened "from time to time" and were "very sad", Mr Key said.
"My understanding is that people were injured and not killed as a result of that. I know that the Defence Force is also looking at ways to try and reduce those risks - but that is always a risk in war zones."
A Court of Inquiry (COI) is set to find that Lance Corporals Pralli Durer and Rory Malone were killed by enemy fire during the Battle of Baghak. An interim finding is that two others involved in the incident were likely to have received shrapnel wounds as a consequence of fire from their comrades.
The battle happened last August 4 after New Zealand troops went to help ambushed Afghan colleagues.
The Chief of Defence Force, Lieutenant General Rhys Jones, said battle procedures were designed to prevent such incidents.
"However, in the extraordinary confusion of a heated fire fight the possibility of injuries as a consequence of fire from our own side is regrettably not unusual.
"Throughout the history of warfare, most militaries in all conflicts have experienced such events. Nor is this new to the New Zealand Defence Force."
A Defence Force spokeswoman said the incident came about because of "diminished situational awareness due to key commanders being wounded or attending those who had been wounded".
Soldiers were trained in fire control, target identification and target indication procedures to minimise the chances of such incidents occurring.
"However, no two contacts are ever the same," she said.
Contributing factors include terrain, enemy, weather and visibility.
"These factors can change the way in which contact with the enemy is initiated/prosecuted and can contribute to mistakes being made."
The COI had considered the "appropriate rules of engagement were followed", Lieutenant General Rhys Jones said.
More detail about the incident would be provided once the inquiry had wrapped up.
The findings were expected to be released publicly in May.
* The New Zealand Provincial Reconstruction Team (NZPRT) had been on operations for four months at the time of the Baghak incident. They were fully acclimatised, and operated as a cohesive unit
* The NZPRT was adequately prepared for its mission
* This was a complex military action
* The insurgents were most likely a mix of 'hardened' insurgents and local tribesman. They carried a mix of medium and small calibre weapons. There was at least one sniper/marksman
* The NZ Army soldiers performed well
* The New Zealand troops were providing in extremis support to the Afghanistan National Security Forces and it is highly likely they would have suffered significantly more casualties than it did, if not for New Zealand's intervention
* Corporals Durrer and Malone were killed by insurgent fire
* Four other members of the patrol were wounded by insurgent fire
* Two members of the patrol were most likely wounded by shrapnel from "friendly fire"
* The "friendly fire" came about because of diminished situational awareness due to key commanders being wounded or attending those that had been wounded
* Evidence received by the Court of Inquiry established that rules of engagement were applied appropriately