New Zealand First leader Winston Peters wants a Commission of Inquiry into the Panama papers to focus on Australian-owned banks.
Mr Peters says New Zealand's reputation has been damaged by the disclosures of the past week into trusts set up in New Zealand.
The leak of 11.5 million documents from Panama-based Mossack Fonseca reveals the existence of 214,000 foreign trusts, more than 11,000 of which have been set up in New Zealand.
Mr Peters says Australian-owned banks in particular should be scrutinised as part of a wide-ranging Commission of Inquiry.
"When I see the ANZ mentioned almost 8000 times, Westpac mentioned almost 1000 times and the principal parent banks in Australia for the ASB and the BNZ now, I know the Aussies are worried and so should the Prime Minister be," Mr Peters told Newshub.
Mr Peters says every national commentator now says New Zealand is a tax haven.
"In the next few days there should be a legitimate full-scale inquiry with the powers to get at the truth and then a commitment to stop secrecy being used against our, and other countries', interests," said Mr Peters.
Mr Peters says these revelations are worse than those examined by the Winebox Inquiry in the mid-90s into transactions New Zealand corporates undertook in the Cook Islands to dodge taxes.
"The Winebox was about our Treasury being robbed by New Zealanders from offshore; this is a case of us robbing other treasuries as well and maybe our own."
There is no evidence at this stage to suggest the Australian-owned banks have done anything illegal here since setting up trusts is allowed under the law.
Acting chief executive of the New Zealand Bankers' Association Antony Buick-Constable told Newshub: "It is unclear exactly what activity Mr Peters is referring to. New Zealand banks are committed to complying with their domestic and international legislative and regulatory obligations, and operating in accordance with those compliance requirements."