UPDATED 2.47PMÂ Australia won't be nominating Kevin Rudd for the top job in the United Nations because Malcolm Turnbull believes the former Prime Minister is not well-suited for the role.
A split in federal cabinet on Thursday meant the Prime Minister was left to make a captain's call on whether to nominate Mr Rudd for secretary-general of the United Nations.
"I have spoken to Mr Rudd in the last hour and advised him of that decision and the reasons for it," Mr Turnbull told reporters in Sydney.
Mr Turnbull told reporters he would not go into the cabinet discussion.
"I do not want to add to Mr Rudd's disappointment, but the threshold point here is when the Australian government nominates a person for a job, particularly an international job like this ... do we believe the person, would-be nominee is well suited for that position?
"My judgment is that Mr Rudd is not, and I've explained to him the reasons why."
Mr Turnbull said it was "far from the most important issue confronting the government".
The decision had nothing to do with Mr Rudd being a former Labor leader, he said, pointing to Kim Beazley's appointment as US ambassador.
"This is no disparagement of Mr Rudd - he is a former prime minister of Australia - but my judgment is that he is not well suited for this particular role," Mr Turnbull said.
Foreign Minister Julie Bishop and Attorney-General George Brandis are understood to have supported the nomination in cabinet.
But a number of conservative ministers including Immigration Minister Peter Dutton spoke against it.
The government has not yet decided who to support for the role.
Earlier Labor frontbencher Anthony Albanese said it was important to back Australians.
"I mean, we are at the Olympics in a couple of weeks - guess what, we back the Australian," he said.
"He is a former diplomat and it is petty that this is an issue."
Acting Labor leader Tanya Plibersek said Mr Rudd was a distinguished Australian who is widely respected as a foreign policy expert.
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