Opposition accused of colluding with New Zealand to undermine Australian government

Australia and New Zealand are engaged in a diplomatic spat over claims Kiwi politicians conspired with Australia's opposition to topple the government.

Australian foreign minister Julie Bishop accused the opposition leader of colluding with MPs in New Zealand to out deputy prime minister Barnaby Joyce as a New Zealander.

She claimed Labor leader Bill Shorten used the "New Zealand parliament to undermine the Australian government" and condemned his "treacherous behaviour".

"This is highly unethical, at least. But, more importantly, puts at risk the relationship between the Australian government and the New Zealand government," she said.

Australia's opposition has mocked Bishop's claims, accusing her of a "Kiwis under the bed scare campaign".

Joyce - known internationally for his row over Johnny Depp's dogs - said he was unaware of his Kiwi citizenship.

Under Australian law he may be forced to step down as section 44 of the constitution bars dual nationals from sitting in Australia's parliament.

After the revelation was made earlier this week, Australian-born Joyce renounced his Kiwi citizenship. The High Court is to hear his case about remaining an MP next week.

With Australia's government holding a majority of just one seat, Joyce being forced to step down could put the government in jeopardy.

Reporters told Bishop during her news conference that it had been a media enquiry that led to Joyce's dual nationality being revealed.

She dismissed this, even after New Zealand's internal affairs minister Peter Dunne had also tweeted that it was a media inquiry.

This is so much utter nonsense - while Hipkins' questions were inappropriate, they were not the instigator. Australian media inquiries were https://t.co/AwLrMYSapk

— Peter Dunne (@PeterDunneMP) August 15, 2017

Bishop later hit out at a New Zealand MP in the Australian parliament.

"It is extraordinary that a New Zealand member of parliament has allowed himself to be used by a party in a different country with an intent to bring another party in that country down. It is quite extraordinary," she said.

New Zealand Labour MP Chris Hipkins had raised the citizenship matter in parliament, but an Australian Fairfax Media journalist said he had also inquired last week about Joyce's nationality following a tip-off.

Senior Labor senator Penny Wong said Bishop was using a "Kiwis under the bed scare campaign" to divert attention from the government's woes.

After herself being accused of colluding with the New Zealand MP, Senator Wong admitted members of her staff had "had informal discussions with New Zealand friends" but denied this led to Joyce being exposed as a Kiwi.

New Zealand Prime Minister Bill English said it was a "statement of fact" that the controversy could hurt relations between the two countries.

He told reporters: "It's quite a serious issue for them, a one vote majority and the appearance of a New Zealand party being involved in the removing of that majority so I can understand why there was a bit of heat in it.

"But I think as heads cool down and they get on and resolve the issues around Barnaby Joyce then we can get on with the positive relationship.

"This incident, these comments, aren't a measure of the relationship. We have got a good relationship."

The leader of New Zealand's Labour Party, Jacina Ardern, said she was keen to talk to Bishop to improve relations.

Joyce is one of five Australian politicians to recently find out they may not have been eligible to stand for parliament.