Societies that support the National Library and Archives New Zealand say having them absorbed into a government department will reduce their integrity and independence.
Parliament's education and science select committee is hearing submissions on a bill which will amalgamate the institutions into the Department of Internal Affairs.
The merger is meant to achieve financial efficiencies, effectiveness and future viability of the agencies.
National Library Society president Joanna Woods told MPs on Wednesday the move appears to be very much about the merging of government information.
However, she says the library is the chief repository for public information.
"The National Library is not just another government department which can be bundled up and shoved into some other agency to save money.
"It is a national institution whose integrity and independence is vital."
The society also spoke against the chief librarian position being reduced to a third tier manager, and said they must have more status and be able to engage with the minister.
The Archives and Records Association of New Zealand made a similar plea, saying that the chief archivist also needs to have direct links with other chief executives to encourage them to keep records in their departments.