Archives and Records Association (Aranz) president Joanna Newman said the association was "very concerned" that the review, initiated by the State Services Commission, had been going on without any wider consultation "whatsoever".
The association was opposed to any reduction in the independence of the chief archivist or of Archives New Zealand (ANZ), Ms Newman, of Wellington, said.
It was "very important for New Zealand's democracy" that the independence of the country's national archives not be compromised, she said.
In a recent statement, the association said it was unclear why "radical changes" were being considered for ANZ, which official terms of reference for the "machinery of government" review had stated was a "well-functioning department".
When the independence of the former National Archives had been last threatened, in 1997, the association had joined others in taking legal action against the government.
ANZ is a government department which has overall responsibility for government record-keeping and community archives.
It was formed in 2000 after the separation of National Archives from the Department of Internal Affairs.
It employs about 130 staff and has a budget of about $23 million.
A three-page terms of reference document, obtained under the Official Information Act, states that the review would consider whether "potential efficiency gains" could be made, or if improvements could be made in "addressing digital challenges".
ANZ would fit most closely with either the Department of Internal Affairs or the National Library, the document said.
A group of critics of the proposed changes warned yesterday that the effect of the approach being promoted by the commission would be "catastrophic" for ANZ and its users.
The role of the chief archivist would be undermined, and there was a "distinct possibility" of the eventual closure of one or more regional offices, such as in Dunedin, if senior management sought "efficiencies" or savings, the group warned.
John Timmins, the chairman of the Aranz Otago-Southland branch, said that the important constitutional role of Archives New Zealand would be "severely compromised" if it was included in another government department.
"I cannot see the logic of the State Services Commission reviewing a perfectly well-functioning department.
"It's not broke - don't fix it.
"It's meddling for meddling's sake.
"It's a retrograde step. I can't see the justification for it."
It was also "very unfortunate" that the Government had not opted for "a more open process", he said.
Mr Timmins is the Hewitson librarian at Knox College, Dunedin, and is a former president of Aranz.
In most Western democracies, the independence of national archives was protected by law.
He noted that everyone in New Zealand was affected by local or national government and their associated commercial bodies, such as state-owned enterprises.
ANZ was responsible for ensuring records were properly kept for all these activities, he said.
Approached for comment on concerns about the review, a State Services Commission spokesman said the review aimed to provide "free and frank advice" to government ministers, including on "opportunities for improving service" in the department.
"We're working our way through the process".
He noted the terms of reference paper had said a consultation strategy with stakeholders would be developed if ministers wished to further consider change.
