Survey results suggest campaigning charities are increasingly fearful of speaking out about government policies because of gagging clauses in contracts, and concerns they could lose their funding.
Researchers say 51.6% of the 153 charities surveyed feared losing contracts or grants as a result of criticising government actions.
Nearly a third of the charities thought debate was silenced or actively silenced by Government.
Twenty respondents said that applied to Labour-led governments between 1999 and 2008, and 55 felt it was true of the current National-led government.
The report by Victoria University researchers, titled Fears, Constraints and Contracts, found the funding agreements of 23 charities explicitly stated that they must not make public comment on government policies and actions.
One respondent said charities need to be independent and ensure funding contracts are not turning them into pseudo-government agencies.