New Zealand Auditor-General Lyn Provost will inquire into how the Accident Compensation Corporation (ACC) manages risk at its board level, following a privacy breach.

The ACC has already begun an independent inquiry after a claimant was mistakenly sent details of more than 6700 cases.

The claimant, Bronwyn Pullar, went public about the breach and the matter snowballed when it emerged she knew then-ACC Minister Nick Smith and had contacted him about her case.

Dr Smith resigned his ministerial portfolios last month when it was found he had written letters for Ms Pullar without declaring a conflict of interest.

The Auditor-General will inquire into ACC policies and practices for managing risks relating to conflicts of interest, legal compliance and communications between board members and clients and staff. The investigation will cover policies and practices when claimants contact board members.