ACC Minister Judith Collins has gone into bat for the senior manager who was told of a potentially massive breach of client privacy in December but didn't do enough to investigate it.
ACC chief executive Ralph Stewart this week confirmed reports that in August last year a case manager accidentally emailed a spreadsheet with information about other clients to a long-term claimant.
About 9000 records were sent relating to about 6700 individuals giving information including their names and claim numbers.
He revealed that Philip Murch, ACC's national manager of Recover Independent Services, first learned of the potential breach during a routine meeting with the claimant in December but didn't inform his superiors.
"We didn't do enough at that point," said Mr Stewart.