It was lucky that a no sensitive details were in the folder, Tolley said, adding such incidents damaged public trust. But at the time she rejected any suggestion that MSD was not trustworthy with personal data.
The breach is deeply embarrassing as it comes at a time when the Government is trying to persuade non-government organisations (NGOs) to share detailed, sensitive information about their clients.
It also gives fresh ammunition for Opposition parties to attack National's much-vaunted social investment approach, which depends on greater information-sharing among agencies.
Last week the Privacy Commissioner, John Edwards, released a highly critical report about the Government's policy of requiring community groups to give up data about their clients if they wanted state funding.
The policy was "excessive" and breached privacy rules, the report concluded.
Edwards said there was a risk that the new funding arrangement between MSD and NGOs could deter some people who were in need of support.
The new MSD contracts investigated by Edwards would make the provision of personal, detailed client data a condition of Government funding. Community groups cannot opt out of the arrangement.