The Privacy Commission says mandatory reporting of privacy breaches could help safeguard personal information, following a breach by Transport Agency on Wednesday.
The agency circulated about 1,000 personal and business e-mail addresses of people who have a special account to pay road tolls.
The emails were sent to notify account holders whose credit cards had failed to top up automatically, but included the names and addresses of other account holders.
The commission says the release of the e-mail addresses, as well as ACC's recent privacy breach, shows more needs to be done to prevent personal details being divulged.
Assistant privacy commissioner Katrine Evans says reporting a breach of privacy is voluntary, but the Government is now considering making it mandatory.