HE wanted the Federal Government's support for the top job at the United Nation's but now that he's missed out on PM Malcolm Turnbull's backing Kevin Rudd has issued a statement. 

"It would have been the first time in the United Nations' 70-year history that Australia offered a candidate for UN secretary-general," Mr Rudd said in a statement this afternoon. 

"It would have reflected well on what our nation can offer to the world - as a middle power with relationships across the world, including the developing world, smaller states, the Commonwealth, our Pacific Island friends and of course our partners in Asia."

Mr Rudd also said Turnbull had emailed to him to say he would back his bid - in September last year.

 "I contacted you for guidance on how I should address the matter of your previously stated support to me for my candidature when I met Foreign Minister Julie Bishop at the UN Geberal Assembly," he wrote. 

"You in fact sent me a message on your preferred Wickr system where you stated that you and the FM (Foreign Minister) were 'as one' in your support of my candidature."

Earlier Mr Turnbull said his party's decision to refuse support had nothing to do with politics.

Rather, the PM said it came down to Mr Rudd's lack of suitability for the role. 

"This decision has got nothing to do with Mr Rudd's party, nothing at all," Mr Turnbull said at a press conference this afternoon.

"I think you understand that. I think Australians will understand that. This is based on - this is a judgement about Mr Rudd's suitability for that particular role.

"There are many examples, as you know, of Coalition governments supporting people from the Labor Party or former Labor ministers and politicians in important positions. 

"I mean, Kim Beazley's term as ambassador to Washington was extended under our government in the last term.



"That's just one example, there are others, but I can assure you that this is not a partisan issue.

"This is a considered judgement about Mr Rudd's suitability for the role in question, that is to say Secretary-General of the United Nations.

"Now, I know it is - there are many political factors that people want to speculate about, but there is a fundamental threshold point, and it is this: Does the Government believe, do we believe, do I as PM believe that Mr Rudd is well suited for that role?

"My considered judgement is that he is not. Now, he is - not everyone is well suited for every role.

"This is no disparagement of Mr Rudd. He is a former prime minister of Australia. But my judgement is that he is not well suited for this particular role."

Mr Rudd worked at the Department of Foreign Affairs and Trade during the 70s and 80s - a period which included stints in embassies in Stockholm and Beijing. 

Foreign Minister Julie Bishop is understood to have supported Rudd's bid to take the top job and earlier today Labor's Acting Opposition Leader Tanya Plibersek said it would be extraordinary for Mr Turnbull not to back a bid a by a fellow Australian. 

He returned to Canberra in 1986 and worked for DFAT for two more years before entering the political realm.