The Beehive was told about Winston Peters' private meeting over his superannuation payments a fortnight ago and before it was leaked to media, the Herald can reveal.

The Ministry of Social Development told its minister Anne Tolley on August 15 under the 'no surprises' policy that it had met with NZ First leader Winston Peters about his superannuation payments - but Tolley has denied the leak came from her office.

News of that briefing comes as Peters questions how news he had to repay money for superannuation overpayments made it to the media, saying it would be a 'criminal' action for his personal information to be leaked.

The Prime Minister's Office has been asked if Tolley's office passed on the information about Peters but has not yet made a response.

Any suggestion that National leaked Peters' personal troubles could have a damaging effect on its chances forming the next Government with his New Zealand First Party.

Peters revealed on Sunday that in July he had paid back overpayments of superannuation between 2010 and 2017, saying he had repaid it as soon as he was alerted to it by the Ministry and did not know how the error that led to the overpayments was made.

Peters disclosed it after inquiries from Newshub while Newsroom also reported details on the case, including that MSD had discovered it while processing the superannuation application of his partner, Jan Trotman, a few months ago.

A spokeswoman for Tolley confirmed to the Herald that on August 15 she was told under the 'no surprises' policy that MSD staff had met with Peters about his superannuation payments.

"MSD advised they were satisfied with the outcome of that meeting."

Tolley would not be interviewed, but a spokeswoman said she denied it had been leaked from anyone in her office.

"MSD takes privacy breaches of personal information very seriously. As it's operational, it's not appropriate for the Minister to comment further.

National's campaign chair Steven Joyce has denied National was behind the leak, saying he had not known about the issue until it became public on Sunday.

"All I know is it's got nothing to do with us.

I have no idea where it came from so I'm not going to suddenly conject or blame people. I checked with National Party people today and nobody as far as I can see or who I spoke to had any idea about it."

A spokeswoman for the Ministry of Social Development said "routine checks" would be done to ensure no private information had been passed on by someone at the Ministry.

"We have no reason to believe that any personal, private information has been passed to a third party. Given the high profile nature of this case we will be undertaking some routine checks to make sure this is the case."

MSD would not provide further details on the case, including whether it was its own administrative error that caused the problem.

"While we appreciate the level of public interest in this case, the Ministry holds a great deal of very personal information that we have a duty of care to protect. It is not our information to share. As stated by Mr Peters, we have been in contact and the matter has been resolved to the Ministry's satisfaction."

National leader Bill English and Labour leader Jacinda Ardern were reserving judgement on Peters yesterday, saying it was a matter for him to deal with.

English said there were clearly questions that would be asked and it was up to Peters to decide how to answer them.

He said he would be concerned if someone working for MSD or IRD had leaked details about Peters' personal circumstances.

"People expect them to be treated confidentially."

Labour leader Jacinda Ardern said she would not be asking Peters for an explanation or more information.

Asked whether Peters should release his correspondence, Ardern said "transparency is always helpful" while adding "that's a question for Mr Peters".

Peters said it was unclear how the overpayments happened, but MSD had not found any wrongdoing and were satisfied with the way the matter was settled. "We tried to resolve how this had happened and we could not. There had been an error."

He denied misleading the Ministry about his relationship with Trotman, saying she had been with him when he signed up for the super with an MSD officer. He had looked at his initial application form again but would not say if he had ticked a box disclosing he was in a relationship or not.

Peters has refused to release documents relating to the overpayments but said as far he was aware he had been getting the payment above the rate he was entitled to.

Because Trotman was not on super it is likely Peters should have been on the payment for 'singles' living with others, but was instead getting the payment for single people living alone, which was about $28 a week more. That totals about $10,000 in overpayments and Peters could also have been charged interest and penalty fees on top of that.

There is no separate rate for people on super who are in a relationship with a partner who is not yet eligible for super. Once both are eligible for super, the rates change.

TIMELINE:

11 April 2010

: Winston Peters turns 65. He is not a member of Parliament at the time.

Soon after: Peters applies for superannuation, saying he went with his partner Jan Trotman and spoke to a Ministry of Social Development officer.

September 2011: Peters gets back into Parliament

16 July: Green co-leader Metiria Turei makes admission of historic welfare fraud at Green Party conference.

Mid July: MSD contacts Winston Peters to advise of an overpayment in his superannuation. Peters repays within 24 hours.

15 August: MSD tells Minister Anne Tolley it met with Peters about his superannuation under the 'no surprises' policy and was satisfied with the outcome.

August 26: Newshub questions Peters after a tip-off about superannuation overpayments. He refuses to answer.

27 August: Peters issues a statement revealing the repayment. Refuses to release the letters or his paperwork applying for superannuation.
Tolley denies her office leaked it. National's campaign chair Steven Joyce denies National was behind the leak.