Defence Minister Senator David Johnston.

Defence Minister Senator David Johnston. Photo: Alex Ellinghausen

The Abbott government appears to be quarantining uniformed personnel from looming Defence Department job cuts even though its own figures reveal they are up to 41 per cent more expensive than civilian public servants who can play crucial roles in protecting Australia.

Government figures show superannuation, allowances and other extras paid to uniformed Defence workers makes them from 15.2 per cent to 40.9 per cent more pricey than an equivalent ranked person in the Australian Public Service.

Staff with military super funds receive government contributions of 18 per cent to 28 per cent a year, depending on length of service.

New details about the breakdown of cost between civilian and uniformed personnel comes as civilian public servants at the department await job cuts which may be dealt to them by the Commission of Audit or through the federal budget.

Defence Minister David Johnston has said having 21,000 public servants running 56,000 uniforms was unsustainable.

The opposition's parliamentary secretary for defence, Canberra MP Gai Brodtmann, said she urged the Abbott government to rethink its strategy. ''Defence has an integrated workforce where civilian and military work side by side,'' she said.

''Any cuts to civilian staff will most certainly be felt by the military - you cannot cut one and think that the other won't be adversely affected.''

She said civilian defence workers were integral to the Australian Defence Force's capability and included highly specialised staff such as those within the Australian Signals Directorate and the Australian Geospatial Organisation.

A Defence spokesman said: ''The government has not made any announcements regarding changes to the Department of Defence Australian Public Service or Australian Defence Force workforces.''

Australian Strategic Policy Institute analyst Mark Thomson said the government believed uniformed personnel were essential because they were available for deployment.

Front-line experience also had given them much-needed expertise when it came to making decisions from a desk in Canberra about issues such as buying equipment.

However, Dr Thomson said by quarantining uniformed personnel from jobs cuts the department had unnecessarily limited its options.

Department of Defence secretary Dennis Richardson, in a speech in November, said more than 20 per cent of his organisation's civilian workforce were former ADF members. He noted that within the past 10 years more than 1000 ADF members had been deliberately civilianised to lower costs.

''We have an integrated workforce where many civilians report to uniformed personnel and many of the latter report to the former,'' Mr Richardson said. ''Try telling someone in the special operations command that a civilian in the Australian Signals Directorate is 'back-end' and, by implication, not essential to the task at hand.''

While Mr Richardson said it was important to ensure staffing was done cost-effectively, he also said the ratio of civilians to uniformed personnel had ''not changed a lot over the years''.