Mr Rudd has been openly canvassing global and domestic support for his candidacy for some time and the fraught matter of whether to back him will now go before cabinet.

Various government figures understood to be cautious about throwing their support behind him.

"Kevin Rudd has requested that the Australian government nominate him and as [Malcolm Turnbull] has indicated on a number of occasions that will be a matter for the cabinet," Foreign Minister Julie Bishop told Sky News.

Immigration Minister Peter Dutton said in April Mr Rudd was behaving like a pest, and should take up a more normal retirement hobby "and play golf or buy a caravan".

"Kevin was never happy just running Australia. He believed he was always destined to run the world," he said. "Kevin's ego makes Donald Trump's look like a rounding error."

A spokesperson for Mr Rudd said he “respects the internal processes of the Australian government".

"He also respects the fact that the government has many other priorities at this time, having just been returned to office. “

Candidates must be nominated by their governments. There are 12 people in the race, including former New Zealand PM Helen Clark, former UN climate chief Christina Figueres and several candidates from Eastern Europe, which is due for a stint in the leadership role.

For that reason and the strong desire for a female secretary-general, Mr Rudd's chances have been described as marginal but he believes circumstances can allow him to sneak through the middle.

Opposition Leader Bill Shorten, who served as a Rudd government minister and was instrumental in his fall and return, said the government "should put the national interest first and support an Australian", describing Mr Rudd as someone "suitably qualified from his experience in government and on the international stage". 

- Sydney Morning Herald