Australia's prime minister says he vetoed a predecessor's bid for the top United Nations job because Kevin Rudd lacks the interpersonal skills and temperament to be a candidate.

Prime Minister Malcolm Turnbull has previously declined to explain his reasons for rejecting Rudd's bid to succeed U.N. Secretary-General Ban Ki-moon beyond saying that he was not "well suited for that role."

Turnbull confirmed the reasons Rudd gave The Australian newspaper in an interview published on Friday.

Rudd also told the newspaper Turnbull had initially supported his bid as Rudd spent two years unofficially lobbying governments around the world to support his campaign.

The decision has been interpreted as evidence of Turnbull's diminished influence within his government after recent elections.

Rudd did not immediately respond to a request for comment.