Defence Minister Wayne Mapp has ordered an immediate inquiry after reports businessmen paid for sessions with the defence force's elite Special Air Service (SAS) troops.

Seventy staff from private equity company Direct Capital and several of its partner businesses went to Papakura Military Camp - SAS national headquarters - on October 28 for a training day which ended with a cocktail party, the Sunday Star Times reported.

For $35,000 - $500 per person - participants were put into a dark room while SAS agents with night-vision equipment stealthily took "terrorists" from the group. They also used SAS firearms to shoot at human cut-outs and drank cocktails with war hero Corporal Willie Apiata.

Dr Mapp told media the exercise was not unusual - business groups have visited military in the past - but he was concerned about the use of firearms in the October training.

Most people had a broad understanding of what the SAS did from television shows but it was different to see it in real life, Dr Mapp said.

The October training came about because of a personal relationship with someone in the SAS and was aimed at making money for the SAS Trust.

Such events were not a money spinner, he said.

Many international military groups have similar trusts to fund educational scholarships, help those wounded during training and to cover other expenses not paid for by the government.

Dr Mapp said it was appropriate the SAS would raise money for its trust in this way and operational security had not been compromised.

However, he asked for an inquiry into the events and wanted guidelines set out for future ones, he said.

Defence Force chief Lieutenant General Jerry Mateparae, a former SAS soldier, would head the inquiry and report back within three weeks.

Prime Minister John Key told Newstalk ZB it was not unheard of for the SAS to engage with community and business groups.

Although unusual, it had happened occasionally over the past decade, and the same could be said of elite forces in other countries around the world.

Direct Capital managing director Ross George said the visit was "to use a room, then we returned to Auckland". A spokesman for Dr Mapp told NZPA he had asked for an immediate report about the event, and expected answers today.

He wanted to know whether such events had happened before, how often they were held and who had participated.

"I understand the defence force does interact with the community but this needs to be looked at," Dr Mapp told the newspaper.

Labour defence spokesman Pete Hodgson said it was "comical that our elite force could be reduced to charging grown-up boys $500 to play war games".

And Green MP Keith Locke said the event showed a bias toward the rich and fund-raising for the trust should be done in more traditional ways.

"Giving well-heeled people special access jars with most people's image of a down-to-earth unit dedicated to helping people in trouble."

The SAS said in a statement it had "aligned itself with top-performing New Zealand organisations to share leadership skills with high-calibre and high-performing New Zealanders who strive for excellence".

"In the past this has included the New Zealand All Blacks and the New Zealand Black Sox softball team. 1 NZSAS Group was recently honoured to be able to continue this trend and support business leaders from Direct Capital Limited. This also included executives from some of the country's top companies."

The "interaction" had focussed on leadership, culture and team dynamic, and included a briefing on the SAS culture, ethos and values.

Direct Capital had "indicated a desire" to make a charitable donation to the NZSAS Trust, established in 2004 to support past and present SAS soldiers and their families. Sir Wilson Wineray is chairman of the trust.