Australia's federal government led secret diplomatic efforts to frustrate a New Zealand-led push for nuclear disarmament, according to documents released under freedom of information laws.
Declassified ministerial submissions, cables and emails from Australia's Department of Foreign Affairs and Trade show Australian diplomats worked energetically against nuclear disarmament efforts by other countries, because ''we rely on US nuclear forces to deter nuclear attack on Australia''.
In October last year, following the election of the Coalition government, Australia refused a New Zealand request to endorse a 125-nation joint statement at the United Nations highlighting the humanitarian consequences of any use of nuclear weapons.
Australia objected to a sentence declaring that it was in the interest of humanity that nuclear weapons were never used again, ''under any circumstances''.
New Zealand Foreign Minister Murray McCully said the Government respected Australia's right to take a different stance.
"Australia and New Zealand take different views on issues from time to time. This needs to be seen within the context of a very close working relationship on a range of international issues.
"We were pleased with the overwhelming support for our resolution Humanitarian Consequences of Nuclear Weapons and respect Australia's right to an alternative view."
Green foreign affairs spokesman Kennedy Graham said it was "more of the same" from Australia and was in line with the stance it had taken in the 1980s when he was involved in negotiations over a nuclear free zone.
"It's sad but not a surprise ... They are saying they are safer with nuclear deterrence, we are saying we are safer without it."
He said the logic, if you reversed it, was that the Abbott government believed there were circumstances when it would be in the global interest to use nuclear weapons.
"If you turn the logic that way it's a pretty extraordinary statement.''
A group of 16 nations, including Indonesia, Malaysia, Mexico, South Africa and New Zealand have been working to highlight the humanitarian impacts of nuclear weapons.
This diplomatic campaign was intended to lay the ground for negotiation of a convention that would prohibit nuclear weapons - putting them in the same category as chemical and biological weapons which were already prohibited under international law.
Australia's foreign affairs minister, Julie Bishop, has argued this approach was simply counterproductive.
''[The] argument 'to ban the bomb' may be emotionally appealing, but the reality is that disarmament cannot be imposed this way,'' she said last month.
''Just pushing for a ban would divert attention from the sustained, practical steps needed for effective disarmament.''
However, declassified documents have revealed the government's primary concern was that a nuclear weapons ban would ''cut across'' Australia's reliance on US nuclear deterrence as part of its defence posture.
An Australian Foreign Affairs and Trade department submission endorsed by Bishop last October argued that a nuclear weapons ban ''conflicts with Australia's long-standing position that, as long as a nuclear weapons threat exists, we rely on US nuclear forces to deter nuclear attack on Australia''.
Australia Foreign Affairs and Trade head Peter Varghese bluntly observed that the New Zealand-led humanitarian initiative ''runs against our security interests''.
Australia's diplomacy suffered a blow when Japanese Foreign Minister Fumio Kishida agreed that Japan would sign the New Zealand-led statement. Australian diplomats consulted closely with the US State Department. Email exchanges between Australian diplomats revealed Washington reprimanded Tokyo over its decision.
Anti-nuclear campaigners labelled Australia's intervention a ''weasel statement ... a last-minute rival announcement ... seemingly in an effort to undermine the efforts of pro-ban activists''.
- Fairfax Media