Key Points:

The Navy is finding it difficult to sail, the Air Force to fly and the Army would struggle to take part in combat, according to the Defence Force annual report.

It paints a picture of all three branches of the defence forces hamstrung by a lack of staff and poor equipment.

In the report, the Army said while land forces were "partially" prepared for low level conflicts, it was not equipped to meet higher threat situations, even though it had managed to send a company to Afghanistan.

The report said: "Deficiencies in command and control, firepower, and compatible protection and mobility for combat service support elements would impair effectiveness in conventional military operations, and the more challenging peace support operations."

The Air Force had "insufficient personnel" to meet crew levels and was only "partially prepared" for complex maritime air operations. In the Navy, few of the ships managed to get out to sea as much as planned.

The HMNZ Endeavour spent 50 days at sea out of an expected 100-120 days, HMNZS Te Kaha 99 days out of 140-160, and the HMNZS Canterbury only 95 days out of 140-160.

This was because of a lack of personnel and "equipment and capability issues".

The Navy also did not receive two offshore patrol vessels and four inshore patrol vessels during the year in question, when these had been expected.

Defence Minister Phil Goff said forces worldwide faced a staffing challenge to attract and retain staff.

He said the total number of defence force personnel was at its highest level in seven years. Since 2005 the Government had committed $4.6 billion to develop capability.

It had also injected $4 billion since 2002 to replace outdated equipment in all three arms of the NZDF, making it the best equipped it had ever been.

Former Secretary of Defence Denis McLean - one of seven of high ranking former defence staff who wrote an open letter to the Government criticising defence policy in 2001 - said the retention problem stemmed from New Zealand's defence strategy.

Many servicemen didn't see career development in the forces because they weren't engaged in multilateral operations with larger states who took a different approach to defence.

"At a time when peace operations are not fully supported around the world, people are moving to multilateral arrangements such as Nato in Afghanistan. We don't belong to any of those, which leaves us in this strange sort of limbo land."

Mr Goff said no one was "remotely interested" in invading New Zealand and defence spending reflected this.

Another of the letter writers in 2001 - Air Vice Marshall Robin Klitscher - said he was not surprised by the report's findings.

"I don't see how it's possible to maintain a credible combat capability in any defence force when in effect we are reducing the share of the national treasure we spend on defence."

He said he had no problem with the Government's strategy to re-equip the defence force, but it would not be enough to restore troops' combat readiness to a reasonable level.

Mr Klitscher, now president of the RSA, said New Zealand's defence policies leaned too heavily on our allies to protect our troops when deployed.

Defence Force chief Lieutenant General Jerry Mateparae said in the report that high standards had been achieved at home and abroad as the forces struggled to retain staff.

- Yvonne Tahana, Eloise Gibson