• Read more: Audrey Young: Peters' case highlights an abuse of the 'no surprises' policy
"On that basis Mr Eagleson decided that it was not necessary to advise the Prime Minister or anyone else in the office on the matter."
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.
This morning Peters told the Herald he didn't want comment in detail until he had the full information, and had people working on the matter.
"It reeks of political dirt. I've got something in train someone looking at the full ramifications of it and then I will do what I have to do.
"The consequences of this offence are serious. I can't give you the full answer now because I don't know what their conclusions will be. But this is political dirt and we are not going to put up with it."
Peters said there was no justification for the information to have been disclosed under the "no surprises" policy, overriding his privacy.
Asked if he believed National had leaked his private information to media, Peters said he would be able to comment in more detail soon.
"I'm not making any statement that I can't stand up. But I will get to the bottom of this, that I can assure you."Any suggestion that National leaked Peters' personal troubles could have a damaging effect on its chances of 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. 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 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 the overpayment 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.
"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 judgment 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".
This morning she said the fact the Beehive knew about Peters' overpayments "matters if they are the source" for leaks to the media that came just days later.
"It certainly matters if they are the source," Ardern told the AM Show, saying New Zealanders wanted the election to be a contest of ideas.
"No one is served by there being any sense of dirty politics in an election cycle. Just because Anne Tolley received the information does not mean she was the source of a leak.
"But certainly if there was any involvement there that would be a big disappointment."
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 - the rate for a single person rather than someone with a partner.
Timeline:
April 11, 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.
July 16: 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.
August 15: MSD tells Minister Anne Tolley it met 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.
August 27: 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.