Winston Peters says defence 'covering their butts' over pension overpayments

The Acting Prime Minister spent Tuesday in court again, fighting to repair his reputation.

Winston Peters says it was damaged in a politically motivated leak of his Superannuation overpayments, before the 2017 election.

Peters is suing over what he calls a political hit-job before the 2017 election, when it was leaked to the media that he was overpaid Superannuation by nearly $18,000.

The leak came after then National Ministers Paula Bennett and Anne Tolley were briefed, and he wants $450,000 from them, and one current and one former top bureaucrat.

Newstalk ZB's political editor Barry Soper was called as an expert witness.

"This was an attempt by Winston Peters' political opponents to damage his credibility and do what Bill English wanted - to cut out the middle man, and that [middle man] is New Zealand First."

The overpayment happened because Peters incorrectly filled out his application.

He was given the higher amount for someone living alone, when he was actually living with his partner of 17 years, Jan Trotman.

A Ministry of Social Development staffer says Trotman wasn't there when Peters applied for superannuation, but both Peters and Trotman say she was there.

"Some people in this defence are covering their butts and it's clear as daylight," Peters said.

Bennett and Tolley deny they were involved and are expected to defend themselves in court on Thursday.