Prime Minister John Key has a short-term deposit with a firm specialising in foreign trusts, according to a new register on MP's finances.
This revelation comes as the government responds to criticisms New Zealand is being used by wealthy people around the world as a tax haven, through the use of foreign trusts.
The register containing details of MPs' finances, the Register of Pecuniary Interests, states the prime minister has a short-term deposit with Antipodes Trust Group.
Watch Checkpoint's report on the issue here:
On its website, Antipodes Trust Group touts the use of New Zealand-based foreign trusts to "carefully manage the inter-generational transfer of wealth".
It also lists the benefits of New Zealand's legal structure.
"New Zealand offers a legislated tax-neutral environment for New Zealand based foreign trusts.
"The tax treatment of such trusts is based on the residence of the settlor rather than the trustee so that, provided the settlor and the beneficiaries are resident outside New Zealand and there is no New Zealand sourced income, the trust will not be subject to New Zealand taxation of any kind."
A spokesperson for Mr Key said the cash deposit was registered with his personal lawyer Ken Whitney in the pecuniary register last year as being with Ross and Whitney, but Mr Whitney has since moved firms, to the Antipodes Trust Group.
Mr Whitney had been Mr Key's lawyer for many years, the spokesperson said.
"The difference between this year's pecuniary interests and last year's is that he has changed firms.
"The short term deposit is used to pay for any costs incurred from the prime minister's family trusts.
"The surplus funds are reinvested short term with New Zealand trading banks."
Green Party co-leader James Shaw said it was not a good look for John Key.
Mr Shaw said it raised questions about Mr Key's comments on the foreign trusts industry over the last week since the Panama Papers were made public.
"I certainly don't think there's anything illegal or anything like that has gone on, but I think given the prime minister's defence of the use of these foreign trusts and disclosure rules over the course of the last couple of weeks that it really doesn't play well.
"It really does mean that we need a proper inquiry, that having one tax expert look at it simply isn't going to be adequate for restoring trust."
Antipodes Trust Group was part of the problem revealed by the leak of documents from the Panamanian law firm, he said.
"This firm is, its primary purpose, appears to be from their website, that they help people to set up foreign trusts in New Zealand using our disclosure rules as a way of avoiding tax in their own country, which is exactly the problem that the Panama Papers uncovered.
"So I think you can't say that New Zealand isn't a tax haven, given this kind of operator here."