The Labour Party says the apparent leak of a confidential diplomatic cable is incredibly damaging for New Zealand's diplomats.
The Australian newspaper on Thursday published extracts of what it says is a briefing from the New Zealand High Commission in Canberra to the Government in Wellington.
The cable reportedly contains details of the deal-making leading up to Kevin Rudd's resignation as Australia's Prime Minister.
Labour leader and former Foreign Affairs Minister Phil Goff says the leak has the potential to make people in Australia think twice before making confidential material accessible to New Zealanders.
However former diplomat Terence O'Brien says the apparent leak won't damage Australian-New Zealand diplomatic relations and the incident needs to be kept in perspective.
Prime Minister John Key says sometimes these things happen, and the Ministry of Foreign Affairs and Trade is looking into the matter.