Prime Minister John Key could have put New Zealanders at risk by announcing SAS logistics officers have been sent to Afghanistan to gather intelligence for a retribution attack on insurgents who killed five Kiwi troops, Labour says.

Mr Key yesterday revealed United States special forces would "almost certainly" carry out any such attack.

The four officers left last week and were based in Kabul, working with the International Stabilisation and Assistance Force and special forces allies.

The Government announced last month that SAS logistics officers would be sent to Afghanistan after Private Richard Harris, Lance Corporal Jacinda Baker and Corporal Luke Tamatea were killed in Bamiyan province when a roadside bomb - or improvised explosive device - hit their humvee vehicle.

Two weeks earlier Rory Malone and Pralli Durrer were killed in a firefight with insurgents in the same area.

Mr Key said the officers were not combat troops. "They are working on trying to get better intelligence on the IED bombers and those who undertook the attack against our people.

"In the event that we can build that case, because you have to go through quite a legal process, that would allow essentially an attack to be undertaken against those people."

Labour defence spokesman Iain Lees-Galloway said the Defence Force did "what it had to" to keep New Zealand troops safe in Afghanistan. "It doesn't help to be alerting enemy forces to what our troops and American troops could be doing."

Mr Key had "opened a can of worms" because the public would now wonder what the officers' role was.

"It's generally agreed logistics are not the purpose of the SAS."

The duties of SAS troops in Afghanistan should not be up for public consultation, he said. "It should be a conversation that occurs between the chief of the defence and the prime minister."

Greens defence spokesman Kennedy Graham agreed Mr Key should be careful about his choice of words.

"The prime minister sounds like he is being a bit loose if he is talking about an attack."

Tracking down insurgents was supposed to be the job of the Afghan police and military, he said.

"As an international community, we have moved beyond revenge."

A Defence Force spokesman said it would not comment on Mr Key's remarks or Labour's concerns.

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