Kevin Rudd, the Australian Prime Minister, found himself embroiled in the latest round of Antipodean sibling rivalry this week, after derogatory briefing papers about his New Zealand counterpart were accidentally leaked to the press.

The documents, describing Helen Clark, the New Zealand Prime Minister as a left-wing control freak, were handed to journalists accompanying Mr Rudd on a trip to Wellington.

The briefing notes were compiled by the Australian High Commission in the New Zealand capital, and they state that Ms Clark was renowned for the discipline that she demanded from those around her. They add that she is known for her “tight control of all things Labour undertakes under her leadership”.

“She holds generally left-wing beliefs, with foreign policy perspectives forged during the Vietnam War” — the documents say, in a polite dig at New Zealand’s modest (and controversial) contribution of about 550 soldiers to the Vietnam War, compared with almost 7,700 Australian troops.

John Dauth, the High Commissioner to New Zealand, who was recently appointed as the next High Commissioner to Britain, immediately apologised and the Australian Department of Foreign Affairs issued a statement regretting the circulation of the “outdated” memo. Ms Clark, a famously tough female politician, laughed off the gaffe, describing it as “a bit of a hoot”, and said she did not plan to encourage the long-held Australian-Kiwi rivalry by releasing her briefing notes on Mr Rudd.

“I think it’s a pretty minor thing, I had a bit of a laugh,” Ms Clark said. “If I had my CVs of other leaders fall off the back of trucks, you’d all have a lot of laughs as well.”

After their meeting in Wellington, the two leaders travelled to the Pacific Islands Forum, being held on the Polynesian island nation of Niue.

The tiny atoll, in the middle of the Pacific Ocean and with a population of just 1,500, has been overwhelmed by delegates from 16 countries. With most of the island’s buildings being taken over by delegates and their entourages, Mr Rudd has been reduced to using a diving shop for meetings.

Despite the shared history and relatively close proximity between Australia and New Zealand, trans-Tasman relations have always been highly competitive. Australians tend to look upon New Zealanders as their poorer, quaint bumpkin cousins, while New Zealanders see Australians as obnoxious and brash older siblings.

When it comes to sporting events there is no love lost between the two nations, and the competitive nature of both countries always spills on to the field. In Beijing this week the old rivalry continues.

Despite Australians’ embarrassment at being beaten by Britain in the medal tally at the Olympics, they are consoling themselves by saying: “At least we’re still beating New Zealand.”

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