The chief of army, Peter Kelly, is "bitterly disappointed" about allegations of sexual misconduct at Waiouru Military Camp, saying he "failed" the new recruits' parents.

Watch Chief of Army Peter Kelly on Morning Report:

Seven instructors are being investigated over seven incidents dating back to May last year, ranging from inappropriate relationships to sexual harassment and bullying at The Army Depot, a unit in the army responsible for training new recruits.

Major General Kelly told Morning Report two members of the leadership team were also replaced after he "lost confidence" in them - a strong message, he said, as it was a first in his 34 years in the service.

"I'm bitterly disappointed. The New Zealand Defence Force, New Zealand Army, and that particular unit have worked incredibly hard over the last five years since 2012 to address some of the culture issues around these particular events and they have come a long way.

"And really what has occurred over the last few months is that a small group of instructors, seven in total, have really let the whole of 6500 members of the New Zealand Army down."

Mums and dads trusted the army with their young children, he said. "That's a massive responsibility and we have to be able to live up to it. In this case we have failed."

Major General Kelly said the allegations were brought to his attention on 27 June and the investigation was launched two days later.

In one case, a male recruit came forward and said he had been subjected to bullying, harassment and sexual assault.

Major General Kelly said the man was still in the army, and was being given support.

He said all the allegations were serious and similar cases have ended up in court or court martial in the past.

He also encouraged other people to also come forward.

Change takes time

Karina Andrews, was a key influence in setting up of Operation Respect, which the Defence Force launched in March 2016 to reduce sexual misconduct within its ranks.

Ms Andrews said in an ideal world, sexual misconduct wouldn't be happening in the Defence Force, but that's not the reality.

"The type of changes they are trying to make are going to take time to make. You've got to weed out a whole old culture to being a very new normal."

"They are now pointing the finger at the people who are in control. If they did not know what was going on, they should have known what was going on and now they are going to be held accountable."

Ms Andrews said that wouldn't have happened five or 10 years ago.