Deputy Prime Minister Winston Peters claimed his privacy was breached when details of his superannuation payments were leaked to media.

Deputy prime minister Winston Peters has had his claims for damages dismissed after it was revealed his superannuation was overpaid for seven years.

Peters appeared before the High Court in Auckland in 2019, suing the Attorney-General on behalf of the Ministry of Social Development (MSD), the ministry's chief executive, the State Services Commissioner and former National Party ministers Anne Tolley and Paula Bennett.

He alleged his privacy was breached when details of his seven-year national superannuation overpayment were leaked in 2017 by an unknown source to the media, weeks out from the election.

A judgment released on Monday found the court was unable to pinpoint the source of the leak and Peters' claims for damages and declarations were dismissed.

In 2019, Peters told the court details of his superannuation payments should never have reached the ministers, and claimed the leak to journalists was a deliberate attack on his reputation.

He claimed the Government departments and officials breached his privacy in advising the ministers of his superannuation, and accused the officials of being reckless and acting in bad faith, which the Crown denied.

GETTY IMAGES Paula Bennett arrives at the High Court in Auckland.

Peters had sought $450,000 in damages from each of the named defendants, meaning a total of $1.8 million if he pursued all monetary claims listed in early court documents.

In November, Peters accepted Tolley and Bennett were not the source of the leak or responsible for it.

At the time, Chief High Court judge Justice Geoffrey Venning reserved his decision.

In the judgment, released on Monday, Justice Venning said Peter's private information about the payment irregularity should not have been disclosed to media.

Fiona Goodall/Getty Images Deputy Prime Minister Winston Peters appeared before the High Court in Auckland in 2019, suing the Attorney-General on behalf of the Ministry of Social Development (MSD), the ministry's chief executive, the State Services Commissioner and former National Party ministers Anne Tolley and Paula Bennett over an alleged privacy breach.

Peters had a "reasonable expectation" that the details of the irregularity would be kept private and not disclosed to parties who did not "have a genuine need to know about it".

"This was a deliberate breach of his privacy with the intention of publicly embarrassing him and causing him harm," the judgment said.

If Peters could have identified who disclosed his private information to the media then damages in the region of $75,000 to $100,000 in total "might have been appropriate", it said.

But he could not make out a claim against any of the defendants and the case was dismissed.

In a statement, NZ First Leader Winston Peters said the case had caused considerable stress.

"It is seriously welcome to see that Justice Venning confirmed that this was a deliberate and malicious breach of privacy done with the intent to damage my reputation and cause harm."

Peters said the case was difficult as despite evidence of malicious behaviour, he had to prove who did it.

"While we are disappointed we could not prove who deliberately leaked that data, the ruling makes clear MSD contributed to the error," Peters said.

"We hope that MSD reflect on their role in this matter."