New Zealand is poised to toughen its disclosure rules for foreign trusts in the wake of the massive data leak known as the "Panama Papers."

Tax expert John Shewan on Monday released a report recommending a big increase in the amount of information disclosed when a foreign trust sets up, as well as increased annual reporting requirements and enforcement.

Prime Minister John Key said that officials still need to review the government-commissioned report but he thinks most of the recommendations are reasonable and will be implemented.

In April, the Washington-based International Consortium of Investigative Journalists identified New Zealand as among 21 tax havens used by Mossack Fonseca, the Panama law firm at the center of the offshore accounts scandal.

Key rejected the characterization of New Zealand as a tax haven.