The Government is accused of running a deliberate policy of keeping information secret which should be made public under the Official Information Act.
The Labour Party says its requests for information are consistently fobbed off by departments and ministers.
Deputy leader Grant Robertson said the Government has a clear strategy of delaying and obstructing requests for information.
Mr Robertson said ministers take advantage of the fact the Ombudsman's Office does not have the resources to do its job properly.
The Council of Trade Unions has similar complaints. CTU president Helen Kelly said delaying tactics or simply refusing to make information public are typical of the response the CTU gets to the requests it makes.
But Internal Affairs Minister Chris Tremain rejected the accusation. He said sometimes a request involves so much information that ministerial offices have to take more time to deal with them.