The federal bureaucracy is openly breaking the law by turning away job seekers who don't hold security clearances.
The Public Service Commission is investigating more than 50 job advertisements that allegedly breach the Public Service Act.
The list of online ads, which Fairfax Media compiled earlier this month, involved 17 recruitment firms offering work in Commonwealth agencies across Australia.
Most ads explicitly excluded candidates who lacked a clearance, describing past security vetting as a "minimum requirement", "essential" or "mandatory".
Another eight ads said the agencies would consider applicants without clearances but warned that people who were already vetted would be preferred – discrimination that is unlawful but nonetheless rife in Canberra.
Several ads were withdrawn or rewritten soon after the commission received the list.
Two senior public servants who work in staffing, speaking on condition of anonymity, said agencies had little choice but to breach the act.
They were often restricted to hiring temporary workers and couldn't afford to wait months for security vetting, which can cost almost $10,000.
Job seekers are not allowed to pay for their own vetting; employers must sponsor the applications. This leaves some government job vacancies effectively open to former public servants only.
However, the act requires all employment decisions to be based on merit and demands that jobs be open to "all eligible members of the community".
The commission tells public service agencies and recruitment firms they must not "exclude applicants who are not holders of a current security clearance where they indicate a willingness to undergo the clearance process".
Almost all federal bureaucrats now require a clearance, which used to be limited to senior executives or officers working with defence and intelligence documents.
The Auditor-General reported recently that the Australian Government Security Vetting Agency was struggling to cope with its workload. It completed just over half of clearances within its target time frames, which ranged from one to six months.
A spokesman for the Recruitment and Consulting Services Association said the firms that published the allegedly discriminatory job ads had acted on their government clients' instructions.
"[Association] members and professional recruitment firms respond to the requirements of their clients in advertising for roles."
The spokesman said the association was unable to comment on public service recruitment policies and referred questions to the government. However, the recruitment firms would not name the agencies that had listed the jobs, which covered a wide range of roles and levels, mostly for fixed-term contracts.
A former public service commissioner, Australian National University public policy professor Andrew Podger, said "there appears to be reason for concern as there is clear guidance from the commission that having a security clearance should not be a selection criterion, as it is not a reflection of merit".
"In cases of urgent and temporary appointments it may be justified as a requirement in order to get the work done, but it is not clear from the job descriptions given that many were genuinely urgent and temporary," he said.
Australian Human Resource Institute chairman Peter Wilson, who is a former federal Treasury executive, said public servants appeared to be caught between the law and today's ramped-up security culture.
"My empathy is with the public servants, whom I have very high regard for," he said.
"They're just trying to get the job done and there are these unintended consequences. That's the dilemma they're dealing with."