The Commonwealth Ombudsman has urged the powerful Parliamentary Joint Committee on Intelligence and Security to remove Home Affairs Minister Peter Dutton's power to redact its reports, saying no other minister has that ability.
Security agencies were granted greater access to encrypted messages last year, through laws that were rushed through on the final sitting day of 2018.
The Commonwealth Ombudsman has oversight of the scheme, however the laws passed last year gave Mr Dutton the power to delete content from Ombudsman reports before tabling them.
The power is only to be used if the information contained in the report could reasonably be expected to prejudice an investigation or prosecution or compromise an interception agency's operational activities.
But the Ombudsman has told the committee that power should be removed or significantly curtailed.
"Specifically, this power is not available to a minister in any other legislation under which the Ombudsman may issue a report and, in our view, is inconsistent with the Ombudsman's role as an independent and impartial office," Commonwealth Ombudsman Michael Manthorpe said.
Mr Manthorpe argued the power was in fact redundant as a separate part of the act states that reports must not contain information that could prejudice an investigation or compromise an agency's operational activities.
His office also routinely asked agencies whether draft reports contained operationally sensitive material that should be removed, and the office only inspected and reported on old records to avoid undermining any ongoing operations.
"We suggest that [the clause] is inconsistent with the office's independence and unnecessary," Mr Manthorpe said.
"We ask the committee to consider recommending that it be removed."
Failing that, Mr Manthorpe said the redaction power should be instead transferred to the federal attorney-general to avoid a situation where Mr Dutton could redact information about his own agency.
There should also be a requirement to show which parts of the report were redacted and under what section of the act, Mr Manthorpe said.
A spokesman from the Department of Home Affairs said the power was created to protect sensitive operational information, or sensitive commercial information, from unintentional public disclosure.
The minister has not used this power to date, he confirmed.