Wellington, March 2 NZPA - The involvement of New Zealand Special Air Services (SAS) troops in gun battles in Afghanistan does not put New Zealand at increased risk from terrorists, Prime Minister John Key said today.

Mr Key yesterday revealed that up to 15 SAS troops were involved, with Afghan security forces, in a battle against insurgents in Kabul following a car bombing last Friday.

Some members of the SAS were fired on by insurgents, and they returned fire. Some of the insurgents were wounded but blew themselves up before they could be detained.

Sixteen people, including civilians, died in the incident.

Mr Key today said there was no evidence to support the suggestion New Zealand could be a terrorist target because its troops were actively involved in such battles.

"There's no evidence through the MFAT (Ministry of Foreign Affairs and Trade) sources, or others, that it's likely to have any impact on New Zealand," he said.

"This is United Nations sanctioned (action).

"Contrast that with Iraq, where it was more a ... view taken by the United States and the United Kingdom to go into Iraq."

New Zealand troops did not shoot anyone dead in last Friday's incident, and nor were any of them injured.

However, Mr Key said there was always concern about the possibility of New Zealand casualties.

"No one can honestly ... rule out the possibility of casualties in Afghanistan but our people have been there now for the better part of six months ... at this stage there's been no casualties, our people are very well trained and they're very careful but there are always risks," he said.

"As Prime Minister of New Zealand, I was aware of that risk when I signed up to ask how many wanted to serve in Afghanistan."

Meanwhile, a security expert says the Government was right to reveal the SAS involvement in the gun battle.

Dr Ron Smith, co-director of Waikato University's international relations and security studies programme, said the action was appropriate under the terms of the SAS deployment.

"I think we knew from the outset that their role this time was going to be near Kabul, and mentoring and supporting Afghan security forces, and that's exactly what the incident confirms," he said.

Dr Smith said Mr Key's announcement was a new development in the Government's attitude to SAS activities.

"We've had, for a long time, a practice of almost being embarrassed about what is going on," he said.

"Although deployments were acknowledged, we didn't want to acknowledge what they were doing."

Dr Smith said international media had drawn attention to those activities, which had obliged the Government to reveal more about them.

"I think that's good," he said.