Australia refused on Friday to back former prime minister Kevin Rudd's bid to be the next Secretary General of the United Nations, saying he was not suited to the job.
Rudd was spectacularly dumped as prime minister by his own Labor Party in 2010, with colleagues subsequently alleging that his office was chaotic and he was difficult to work with.
"This is not a partisan issue, this is a considered judgement," Prime Minister Malcolm Turnbull, who is from the rival Liberal Party, said when announcing the decision in Sydney.
"This is a judgement about Mr. Rudd's suitability for that particular role."
Canberra revealed earlier this month that the Mandarin-speaking Rudd, who is based in New York as head of the Asia Society policy institute, was keen to lead the global body.
Candidates must be nominated by their governments and Turnbull said he made the decision not to put Rudd forward after consulting with his cabinet.
Turnbull said he explained his decision to Rudd -- who brought Labor out of the political wilderness in a 2007 election landslide -- but would not elaborate on his reasons.
"When the Australian government nominates a person for a job, particularly an international job like this, the threshold question is, 'Do we believe the person, the nominee, the would-be nominee, is well suited for that position?'" he asked.
"My judgement is that Mr. Rudd is not, and I've explained to him the reasons why."
Rudd, who was dumped as prime minister by his colleagues in 2010 for Julia Gillard only to be reinstalled briefly as Labor faced an electoral wipeout in 2013, had the support of Turnbull's Foreign Minister Julie Bishop.
Labor had also argued it was in the national interest to have an Australian in the role but reports said there was little enthusiasm for him within the government.
After months of public campaigning, debates and open hearings, Security Council ambassadors must decide who will succeed Ban Ki-Moon at the world body from January 1.
Among the top contenders are Argentina's Foreign Minister Susana Malcorra, Slovenia's ex-president Danilo Turk, New Zealand's ex-prime minister Helen Clark and Antonio Guterres, who served as Portugal's prime minister and headed the UN refugee agency.