Fifty-five former Australian ambassadors and high commissioners have written an open letter to the new Australian Prime Minister Anthony Albanese, urging him to sign and ratify the Treaty on the Prohibition of Nuclear Weapons (TPNW) “without delay”.

Their appeal comes as Australia sends a delegation, led by Labor MP Susan Templeman, to Vienna this week to observe the first United Nations meeting (21-23 June) of states parties to the landmark disarmament treaty.

The UN meeting will be the first intergovernmental gathering focused on addressing the threat of nuclear weapons since Russia President Vladimir Putin’s invasion of Ukraine and multiple threats to use nuclear weapons.

Mr Albanese has been a vocal supporter of the TPNW, proposing a resolution in 2018 that committed the Australian Labor Party to sign and ratify it in government.

The previous Coalition Australian Government refused to participate in the negotiation of the TPNW at the UN in 2017.

In their letter, the former diplomats warn about the threat posed by “Russia’s nuclear sabre-rattling over Ukraine and, more generally, by the abysmal state of relations between the United States and its two most powerful nuclear-armed rivals”, saying: “Unless we chart a new course, nuclear weapons will almost certainly be used again, with predictably catastrophic consequences.”

They reject the former Coalition Government’s claims that the TPNW undermines the half-century-old Non-Proliferation Treaty and conflicts with Australia’s obligations to the United States.

“Membership of the TPNW is compatible with Australia’s alliance commitments and will make a positive contribution to the security objectives we share. We have previously signed and ratified treaties – on landmines, cluster munitions and nuclear testing – to which the United States is not a party,” they wrote.

The letter’s  signatories include former diplomatic representatives to the US, United Kingdom, China, Indonesia, Japan and the United Nations. Several are experts in the field of disarmament.

They expressed hope that under Mr Albanese’s leadership the goal of a nuclear-weapon-free world would be reinstated as “an Australian foreign policy priority” and Labor’s commitment to the TPNW would be “swiftly realised”.

“Making meaningful gains in eliminating the most destructive weapons ever invented is as crucial for Australia’s security as it is for the security of people everywhere,” they said.

They added that joining the TPNW would allow Australia to work with “like-minded states” to help avert the use of nuclear weapons. “This is a sensible and overdue step. We urge you to take it without delay,” they said to Mr Albanese.

The Australian-founded International Campaign to Abolish Nuclear Weapons (ICAN), which won the Nobel Peace Prize in 2017 for its work on the TPNW, helped coordinate the letter.

“This appeal demonstrates the broad support for the TPNW among Australia’s foreign policy establishment,” said Gem Romuld, ICAN’s Australian director. “It was a mistake for the previous government to abstain from the negotiations on this crucial treaty. But it isn’t too late to join – and we expect the new government to follow through with its promise to do so.”