The Defence Force is stretched, and is doing more with fewer staff than at any time since World War II, Defence Chief Air Marshal Bruce Ferguson says.

He told the RSA conference in Wellington yesterday that he hoped to get funding in next year's Budget to recruit more staff.

"We are fully engaged right now, never more so than at any time since World War II, and we are doing it with less personnel than we've ever had. It is true there are budget constraints and I'm at maximum ability to spend the money at the moment.

"What I'm doing right now - it's being done independently - is a review of what I think we need in resources, basically personnel, and what Government expects in its outputs. There is a gap there in my view right now - it's the expectations of what defence forces need to do and my capacity to meet them."

Air Marshal Ferguson said a major review involving the State Services Commission, Treasury and an independent assessor was under way to look at the capabilities of the three Services. Essentially, it was looking at manpower.

He expected to make a case before the end of this year for extra funding to be included in next year's Budget.

Even if there was a substantial increase in funding, recruitment could be a problem.

"Our recruiters are working flat out and there aren't enough people coming forward," Air Marshal Ferguson said.

The only exception was in pilot recruitment, where for the first time in 15 years the Air Force's pilot intake was above capacity.

With new equipment, including the Army's light-armoured vehicles, seven ships for the Navy, and upgraded technology for the Air Force, the Services required more people, especially young people who were technically knowledgeable.

Air Marshal Ferguson's comment coincides with a move by the RSA to push for a major review of defence policy.