New Zealand’s acting prime minister, Winston Peters, is suing two National party MPs, a slew of public servants and a government ministry for breach of privacy.

Peters, who is currently acting PM in Jacinda Ardern’s absence, alleges that Anne Tolley and Paula Bennett breached his privacy by leaking his superannuation documents to the media.

Peters, who was the case’s first witness in the high court on Monday, is also suing the attorney general, David Parker, on behalf of the ministry of social development, the ministry boss Brendan Boyle and the state services commissioner Peter Hughes, saying their ministries should not have provided information to the National MPs of his superannuation over-payments.

Peters says his reputation was tarnished a month out from the 2017 general election.

“It is still brought up by my detractors as a slur on my character to this very day,” RNZ reported him saying in court.

“There was no scandal, just a malicious leak which mixes fact with a deliberate falsehood.”

“I find it repugnant and I believe any New Zealander would equally find it repugnant if their private dealings with MSD [ministry of social development] were released to ministers who have no responsibility in the issue. In my case ministers who are my political opponents, a month out from a general election.”

Peters is seeking damages of NZ$450,000 from each defendant named in court documents, for a total of nearly NZ$2m.

New Zealand taxpayers will foot the bill for any damages awarded, and taxpayers are also paying for the Crown’s defence that it was not wrong to share Peters’ details with the National MPs.

The Crown argues Peters was treated the same as any other private citizen and ministers at the time had a “no surprises policy”, meaning they asked ministry officials to inform them of any cases that could be high-profile or draw attention.

The trial is set to last three weeks. Peters has said he isn’t to blame for the superannuation over-payments – which lasted seven years – and the fault lay with the ministry which incorrectly processed a form, and paid him the higher rate of a single person, rather than the lower-rate of a partnered person.

Peters said that in the same month of his 2010 superannuation application, 23 other people in New Zealand made the same mistake on their form, failing to tick the box asking whether they had a partner.

Peters paid back NZ$18,000 to the ministry of social development, after he was alerted to the over-payments.

The former social affairs minister, Anne Tolley, and current National party deputy leader, Paula Bennett, are expected to give evidence in court this week, as well as a number of journalists and some witnesses who have had their identities protected.