UPDATED: 9.56AM Opposition parties are making the most of the Prime Minister being caught out over foreign trusts.

John Key's latest pecuniary interests declaration reveals he has a short term deposit with a firm called Antipodes Trust Group Limited, a company that is a specialist provider of foreign trusts.

SEE ALSO: Little's decision to release tax records a 'stunt' - Key

Mr Key's office said the Prime Minister's lawyer, Ken Whitney, who he's used for some time, has changed firms and heads the company in question. His office said his relationship is with Mr Whitney, rather than with the company itself.

Green Party Co-leader James Shaw said there's no evidence the Prime Minister's used a foreign trust, but his investment is held by a company that has foreign trusts as its primary purpose.

"And that's not illegal, but it's a very bad look," he said.

Massey University's Dr Deborah Russell told Mike Hosking Key's done nothing wrong.

LISTEN ABOVE: Dr Deborah Russel talks to Mike Hosking

"He did nothing illegal. As far as I can tell this is just an ordinary old transaction and the explanation Mr Key has given is perfectly reasonable."

Labour leader Andrew Little is calling on the Prime Minister to sever his contact with his lawyer.

"The Prime Minister should have nothing to do with this. It is wrong, it's a bad judgement call on his part to continue to have this association."

Mr Little is insisting the Prime Minister should release his tax records to show he's never used a foreign trust in the wake of the Panama Papers.

He said John Key needs to prove he has no time for tax dodging.

"There is an issue of the personal integrity of those who can do something about it. I was challenged, I'm happy to rise to that challenge.

"I think people need to know and want to know that the Prime Minister has integrity."