Parts of the federal bureaucracy are also offering payouts to underperforming staff in a bid to get rid of them, in defiance of the government's employment policies.

The practice could expose the Australian Public Service to lawsuits from redundant workers.

Prejudices against so-called ''excess staff'' are detailed in documents obtained under freedom of information laws.

Public Service Commissioner Stephen Sedgwick briefed his minister, Gary Gray, in April on the difficulties in finding new jobs for staff whose jobs had been abolished.

''… It is often the case that staff of lower calibre are made excess, given the need to retain highly skilled staff,'' he told the minister. ''Other agencies (and other areas within agencies) are therefore cautious of accepting excess staff.''

Mr Sedgwick also wrote that, during past redundancy rounds, even agencies in need of more staff manoeuvred to avoid public servants labelled as excess.

A separate Public Service Commission briefing to the Department of the Prime Minister and Cabinet in 2009 said redundancy payouts could be ''part of an effective strategy to target lower-quality staff at a time of downsizing, providing longer-term benefits to the agency''.

However, while the practice is believed to be common, it breaches government policy. The commission's guidelines warn agencies they ''should not use excess staffing arrangements as an alternative to dealing with underperformance''.

Redundancy decisions must be based on whether the job - not the person - is needed.

Employment law specialist Jennifer Wyborn, of legal firm Bradley Allen Love, said yesterday employers ''who use redundancies, voluntary or otherwise, where the positions are not truly being made redundant walk a dangerous path''.

''If employees are covered by an enterprise agreement, they are likely to have access to the unfair dismissal provisions under the Fair Work Act,'' Ms Wyborn said.

''Further, in such situations, employers are unlikely to have complied with the underperformance management provisions of the enterprise agreement and will be open to a claim of breach of the enterprise agreement.''

A commission spokeswoman said yesterday its long-standing view was that redundancies should not be used to get rid of poor workers.

''However, we also consider that where an excess staff situation arises, an agency should approach the matter having regard to its workforce planning needs.''

The spokeswoman said an agency might reasonably want to ensure it kept the ''workforce best placed to enable it to meet its total obligations to government and the community''. ''In that context, an agency might reasonably seek to retain its highest performers with skills still in demand and those with critical skills,'' she said.