Claims of concealed tunnels, buried explosives and priceless planes have swirled around Auckland's old North Head Army fort for decades.

While official records state there is nothing in the sealed tunnels, some Navy officers and even a former Minister of Defence tell a much different story.

In a significant development, the Department of Conservation (DoC) has recently tested for the presence of buried ammunition at North Head, with further testing planned.

Captain Jo Harvey, one of the last Army officers stationed on North Head, says he was responsible for removing ammunition in the late 1950s - but doesn't remember leaving anything behind.

"I would be the one responsible for leaving any ammunition there and I am a responsible person, and I certainly am not aware that I even left one shell on North Head," he told Newshub Nation.

However Naval Petty Officer Vern Rule says he was there when the ammunition was being removed, and the soldiers involved refused out of fear for their own safety.

"The crew moved three shells onto the trucks and then they refused to handle any more, considering it to be suicidal."

Mr Rule says the crew were then charged with a disciplinary offence and sworn to secrecy while the ammunition was simply sealed into the tunnels.

"They said they would go to the media about it and so if the charges to be pulled they were required to sign a declaration never to mention it."

Former Defence Minister Bob Tizard was seemingly positive that not only was the ammunition remaining there, but it was potentially dangerous.

In a recorded phone call in 1992, the former minister said: "I don't think there's any question about this deteriorating ammunition. That's why the place was sealed initially.

"The fear was expressed that if they removed they had to remove the block in the tunnel there would be a danger of producing vibrations that could set the ammunition off so they were not prepared to take that risk."

In January, DoC tested for ammunition and has stated that it shows there no risk to people - but there is further testing planned.

Watch the video for the full story.

Newshub Nation.