The Serious Fraud Office (SFO) says it will give urgent priority to its investigation into allegations of corruption against a former ACC staff member.
Concerns over the former staff member in relation to the lease arrangements and purchase of buildings for ACC offices were given to the SFO by ACC after an internal investigation.
ACC Minister Nick Smith said the issue involved property transactions and government agencies, including ACC, were involved with "large" property dealings.
It involved problems in a number of different centres in New Zealand going back many years.
He had no estimates of the sums of money involved and did not want to speculate.
One staff member had been dismissed for failing to follow policies and procedures, but Dr Smith did not know if anyone else was involved.
The concerns about property dealings go back "many years" because the staff member involved was an employee of ACC for a "good period".
The public has a right that government agency property deals be done "with the highest levels of integrity", Dr Smith said.
"I refused last year to open ACC's new offices in Nelson because of information I had that the taxpayer had not got good value for money."
Dr Smith said it was up to the SFO whether criminal charges were laid.
"I don't want to speculate, the decision about whether criminal charges or whether there's been any illegal behaviour is properly a decision for the SFO, I am satisfied that ACC has referred the appropriate material at the appropriate time to the SFO."
SFO director Adam Feeley told NZPA the case would be given the "highest priority" because it involved a public official.
The SFO investigates two types of cases, large scale (over $10 million) fraud involving investor losses and allegations of bribery, or corruption involving a public official. The ACC case fell into the latter.
ACC chief executive Jan White said because the situation was being considered by the SFO, ACC would not be making any further public comment at this stage.