UPDATED 8.22pm The Privacy Commissioner has found that Westpac breached the privacy of investigative journalist Nicky Hager - by releasing his personal information to the Police without a warrant.

LISTEN ABOVE: Senior litigator and privacy specialist Kathryn Dalziel spoke to Larry Williams about the case

In the lead up to what has since been ruled an unlawful Police raid on Mr Hager's home in 2014, Police asked Westpac for more than 10 months of Mr Hager's bank transactions.

New Zealand banks can release information to Police without a warrant, if Police say it's needed for an investigation.

The Police falsely said Mr Hager was being investigated for fraud, but provided nothing to support the claim they needed his information, and Westpac didn't ask for any.

The warrantless search of Mr Hager’s banking transactions was kept hidden from him until he obtained a discovery order in the High Court.

The findings are advisory and if Mr Hager wants action he'll have to take his case to the Human Right's Commission.

His lawyer Felix Geiringer said if Westpac says sorry this can all go away.

"If Westpac turn around and say 'yes, we accept it, we got it wrong. We breached Nicky's privacy we can apologise and make amends and we're going to make sure it doesn't happen again,' then the need for a Human Rights Tribunal will essentially be done away with."

Westpac said it has a new policy not to release information to the Police without a production order.

Lawyer Kathryn Dalziel said the Privacy Commissioner's findings in the case has set a precedent .

Ms Dalziel told Larry Williams she'll have to change the advice she gives to clients.

"What the Privacy Commissioner is saying is well you didn't have enough information to be satisfied that this was necessary to avoid prejudice to the maintenance to the law. That's a wee bit of a shift to the way I've understood how that section works."

A claim against the Police for making the request is still before the High Court.