The Morrison government has been accused of breaching disclosure laws by scaling back the peak agency which oversees the release of information amid a growing row over public sector secrecy.

Former Commonwealth ombudsman John McMillan said the government's approach to Freedom of Information was undermining transparency and breaching the spirit of federal law.

John McMillan said the failure to appoint three commissioners can be read by the public service as a message that transparency is not important.

The warning intensifies the debate over a backlog of requests for information by citizens and the media, with the Department of Home Affairs failing to release documents within the legal deadline in one out of four cases.

Mr McMillan said the government should meet the obligations set by Parliament to appoint three statutory commissioners: an information commissioner, a privacy commissioner and an FOI commissioner.