The Chief Ombudsman will launch an investigation into the way the Official Information Act is being used after the election and will include a probe into ministerial offices as part of the inquiry.
The probe comes in the wake of Nicky Hager's book Dirty Politics and questions over OIA information provided to Whaleoil blogger Cameron Slater.
Chief Ombudsman Dame Beverley Wakem said issues which would be examined included government departments having to seek "sign off" from their ministers before releasing information when there was no reason to do so.
She said there was "excessive reference upwards for approval" to release information when there was no good reason for doing so.
The Act was intended to increase Government and ministers' accountability to the public while allowing citizens to have a greater input into decision-making. It was passed in 1982, came into force two years later and has now been operating for 30 years.