Authorities in the Cook Islands say the country's regulatory framework for offshore trusts is better than in most places in the world.
A Wellington-based journalist, Nicky Hager, is calling on the New Zealand government to stop accepting the use of the Cook Islands as a tax haven, following an investigation involving millions of financial documents.
Megan Whelan reports
The Cook Islands was last involved in a tax scandal during the 1990s, when it was at the centre of the so-called wine box affair.
Nicky Hager is part of an international team investigating millions of leaked records of corporate dealings in international tax havens - both legal and illegal.
He says he was investigating a company started in the Cook Islands on what he calls the wild west Winebox days.
"I think that New Zealand should make a high priority of closing down the Cook Islands tax haven. I think that the world would be a better place without tax havens and New Zealand has set up the Cook Islands tax haven. Our government, in effect tolerates it and allows it to keep going. And the sooner that one is closed down, the sooner we set a good example to the rest of the world."
Nicky Hager says tax havens are more about secrecy, and points to companies avoiding millions of dollars of tax. .
But the head of the Cook Islands Financial Development Authority, Jenner Davis, says in 2003, the Cook Islands passed a host of legislation regulating the offshore finance sector.
Transactions today aren't really about secrecy. It's about privacy, often, because the extremely wealthy in the world, that's often what they are seeking with their wealth management structures, so they're not hounded by every financial advisor and accountant. There's nothing secret from the authorities here in the Cook Islands. They can go in and evaluate the files, and evaluate the processes by which the trust companies are monitoring their obligations.
New Zealand's Inland Revenue will investigate links in off-shore tax havens.
The Revenue Minister, Peter Dunne, says Inland Revenue will investigate any allegations relating to tax avoidance.
Any opportunity we get to track down New Zealand taxpayers who are evading taxes that they should be paying to New Zealand, we will pursue.
The Cook Islands finance minister, Mark Brown, says while wanting to protect confidentiality, the Cook Islands is mindful that it needs to exchange tax information, and has agreements with 16 countries.
He says the Cooks already works closely with New Zealand authorities, and times have changed since the wine box inquiry.
We've spent a lot of time and taken a lot of effort to try and shake this unsavoury reputation, which has followed us around, and I have to say the Cooks has done a lot in the last 10 years. There's been numerous assessments done on the Cook Islands, as well as other countries in the region to make sure that they are complying with international standards.
Mark Brown says there is a lot New Zealand needs to do to in terms of tightening up its own financial services jurisdiction.