Tony Abbott promised to back former New Zealand leader Helen Clark as the next UN secretary-general when he was prime minister.
The revelation puts him at odds with Foreign Minister Julie Bishop, who has signalled the government would consider supporting former Labor prime minister Kevin Rudd if he nominated for the UN job and that no firm commitment had been given to anyone else.
However, an exchange of letters obtained by The Australian shows Mr Abbott committing to a joint plan with New Zealand Prime Minister John Key to back Ms Clark to succeed Ban Ki-moon.
