An investigation has found no evidence any Ministerial Services staff leaked information to the media about Winston Peters being overpaid superannuation for several years.

The Department of Internal Affairs interviewed Ministerial Services staff and searched digital records as part of it investigation.

The probe found five Ministerial Services employees had received the information before it was reported by media but there was no evidence they provided the information to any third parties, a Department of Internal Affairs spokesperson said.

"The Department takes privacy seriously, and upholding the confidentiality of information forms part of the Code of Conduct all employees sign.

"If further information comes to light, the Department will undertake further inquiries as necessary."


Two other government agencies - the Ministry of Social Development and Inland Revenue - have also denied any of their staff were involved in the leak.

MSD said in a statement earlier today that all staff that had access to the relevant information had a reasonable business purpose for accessing it, and there is no evidence that this information was passed to a third party".

"The ministry holds a great deal of very personal information about people and their families that New Zealanders trust us to safeguard."

Peters has called in the lawyers and pointed his finger at the National Party as the possible "leak" to the media of the news he had to repay overpayments for his superannuation since 2010, saying it was an attempt to destroy NZ First.

That followed revelations that ministers Paula Bennett and Anne Tolley were briefed on the overpayments by Government department heads under a "no surprises" policy.

National leader Bill English has said he did not believe the leak came from National and was assured by Bennett and Tolley they had not passed on the information.

State Services Commissioner Peter Hughes has defended the decision to inform the ministers, saying it was carefully considered and the Solicitor General had been consulted.

However, English said the Government departments should not have told ministers, given the personal nature of the information. He said the ministers had handled it "with integrity".