Prime Minister John Key said he sought an assurance from his lawyer that he was not linked to Mossack Fonseca, the law firm at the heart of the Panama Papers scandal.

After the papers were leaked last week, Mr Key said he double-checked his investments to make absolutely certain that he had no links to foreign trusts.

That included calling his Auckland-based lawyer, Ken Whitney, whose firm specialises in New Zealand-based foreign trusts.

"I've had a discussion with him to be absolutely, 100 per cent sure because I've got to look down the barrel of the camera and make sure everything's right," he told reporters this afternoon.


In the register of MPs' interests, published yesterday, Mr Key declared that he had a short-term deposit in Mr Whitney's company, Antipodes Trust Group.

The company described itself as a specialist in foreign trusts and promoted the minimal reporting requirements for overseas investors setting up trusts in New Zealand.

Mr Key denied that his disclosure was embarrassing given the current focus on foreign trusts in the fallout of the Panama Papers.

The deposit had been with his lawyer for years, and was held in an Auckland-based bank, he said.

Mr Whitney, as a trust specialist, was covered by the highest anti-money laundering rules in New Zealand, including two-yearly audits.

"He has been my lawyer for well over 20 years. I don't deal with people unless they're highly ethical and do things well."

Most law firms did trust work, he said, though Mr Whitney was "a bit more interested in it".

Mr Key said that the foreign trust industry was "a legitimate business" and was not "the devil incarnate".

Asked why he did not disclose his link to the Antipodes Trust Group when asked about his investments on Monday, he said he had disclosed it years ago and it had only become relevant again because his lawyer had moved companies, taking the deposit with him.

He reiterated that he did not have any investments in foreign trusts. If he did, they would have shown up in the register of pecuniary interests.

Mr Key said he also spent eight hours on Sunday tracking down details about his Singaporean superannuation fund to be certain that all of his investments were above board.