Police say ACC laid a formal complaint alleging blackmail, six days after the minister was informed by the corporation.
The Accident Compensation Corporation has been embroiled in controversy over its dealings with claimant Bronwyn Pullar, who is in dispute with ACC about what was said at a meeting with senior managers after she was mistakenly emailed details of 6500 claimants in December 2011.
ACC contends that Ms Pullar threatened to go public with the private information unless she was given financial support for two years. Ms Pullar denies ever making a threat.
Police have investigated and decided not to take any action, saying no offence was committed.
ACC Minister Judith Collins has faced questions about when she found out about the alleged threat and whether she had any influence on the corporation's decision to go to police.
Over the past few days, the minister has been unable to say whether she discussed referring the matter to police with the ACC board and senior management before the complaint was laid.
On Thursday, Ms Collins told reporters she was notified the day ACC initially contacted police and, therefore, could not have had any influence on the corporation's decision.
"Certainly not. I had nothing to do with the referral to police."
However, police say while initial contact was made the day Ms Collins was informed, the formal complaint was not laid until six days later.
PM standing by Collins
Prime Minister John Key is standing Judith Collins over her handling of the public corporation and its privacy breaches.
The casualty list at ACC grew on Wednesday, with the resignation of chief executive Ralph Stewart and comes a day after Ms Collins announced that ACC board chair John Judge would not be re-appointed and will be leaving at the end of June.
The corporation's deputy board chair John McCliskie and director Rob Campbell are also leaving.
The Labour Party says the current situation at ACC is disgraceful and Ms Collins should be sacked. However, John Key says he still has confidence in Ms Collins and believes she is doing a good job at managing the situation.
The resignation of ACC chief executive Ralph Stewart forced a snap debate in Parliament on Wednesday.
Labour MP Chris Hipkins told the House the mess started with former ACC Minister Nick Smith. Dr Smith hit back, saying ACC was in dire straits financially when he took over as minister from Labour in 2008.
But Labour deputy leader Grant Robertson said the National Government had done nothing but trash ACC's reputation since it came into office.
Labour ACC spokesperson Andrew Little says Judith Collins has used prevarication and obstruction in the early stages of the privacy breach scandal at ACC and has been missing in action until the last few days.
Mr Little told Morning Report Ms Collins is herself the subject of a privacy complaint and has used that and a defamation action against himself and Trevor Mallard to avoid dealing directly with the issue.
ACC board 'sad' at resignation
The ACC board issued a statement on Thursday expressing sadness at the resignation of chief executive Ralph Stewart.
Board chair John Judge said board members believe the vision and strategy planned for ACC by Mr Stewart, which has been signed off, are exciting and full of promise.
He said Mr Stewart's leadership was already starting to change the culture at ACC and his plans to improve services to claimants and levy payers were in the process of being introduced.
Mr Judge said the board must now ensure that the focus of the organisation is on the agreed goals established by Mr Stewart and his executive team.
He believed Mr Stewart's resignation is a great loss for the corporation.