More than 550 public servants at the federal Communications Department will have to compete against workmates in the coming months as they fight for about 425 jobs in a radically restructured department.

But the department says ''fill and spill'' was the fairest way to manage the reduction in jobs at Communications after a voluntary redundancy program held last year.

The move is an escalation of the government's tough public service cost-cutting campaign and could have repercussions across the 165,000-strong bureaucracy which was promised before last year's election that any job losses would be achieved through natural attrition. The news was broken to shocked workers on Friday morning. The process, aimed at cutting 125 jobs, marks a move away from the voluntary redundancies used so far to achieve the government's cull of public service jobs and has been condemned by the public sector union as cruel, vindictive unprecedented, disruptive and divisive.

Departmental secretary Drew Clarke, who will not have to apply for his own job, declined to be interviewed but said through a spokeswoman that staff had been kept updated while the move was being planned over several months.

''The department considers the process currently under way to be a fair and equitable way of managing a redesign and reduction of this scale,'' the spokeswoman said.

''The secretary first addressed all staff in September last year about the need to address a range of priority areas, one of which was our structure. He has communicated regularly with staff throughout the following months as part of a comprehensive process to identify our strategic priorities and inform our new Corporate Plan.''

Communications' workers were given a 17-page document on Friday morning describing the department's new structure and advising rejected job applicants would have three options: apply for a lower-grade job, accept redundancy or redeployment.

A spokesman for Public Service Minister Eric Abetz said the latest cuts were the responsibility of the previous Labor government.

''The reduction in funding is predominately the result of terminating programs from previous budgets,'' the spokesman said. ''It is expected that the reduction in staffing will occur through a combination of natural attrition, retirement, redeployment and, as a last resort, voluntary and involuntary redundancies.''

The department's main union, the Community and Public Sector Union, said it was shocked at the brutality of the move, with deputy national president Alistair Waters saying the tactics were unprecedented. ''This is a disruptive, costly and deeply divisive process,'' he said.

''All it will do is pit colleague against colleague and throw the department into a tailspin.

''Waking up and finding out that your department is cutting jobs is bad enough but then to be told you will have to fight your workmates to hang on to a job is worse.''

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