Frustration is growing within the Defence workforce as crippling computer outages continue to hamper the organisation's highly secure internal network.

Key points: The network has experienced problems for several days and caused disruptions for about 80,000 staff.

The network has experienced problems for several days and caused disruptions for about 80,000 staff. Defence is undertaking a major ICT infrastructure transformation program

Defence is undertaking a major ICT infrastructure transformation program Staff are going home early because they're unable to do their work without IT access

Staff are going home early because the IT failures are preventing them from being able to do their jobs.

The ABC has learnt the "Defence PROTECTED Network", which is currently being upgraded, has experienced problems for several days and caused disruptions for about 80,000 staff.

Defence employees have told the ABC the IT problems are the worst the department has experienced in more than a decade.

"Staff are being sent home early because they can't do any meaningful work with the system as it is," one person with knowledge of the situation said.

"The system issues are also delaying export licences and other regulatory responsibilities of the department," the source said, speaking on the condition of anonymity.

Another department insider said the "crippling" problems meant frustration was growing among Defence staff.

"Productivity has been significantly affected, and it's not like our work stops," the insider told the ABC, also under the condition of anonymity.

"It's not as though ministers can take the day off because the department can't use its computers."

The Defence department confirmed in a statement that there were "some disruptions to the network, which have affected email and document management applications".

"Defence is undertaking a major ICT infrastructure transformation program, encompassing the modernisation of desktop, network and data centre services," the statement reads.

"The complexity and scale of this work has resulted in unplanned service disruptions within the Defence Network."

The Department said its chief information officer was overseeing the ICT upgrades and was working to minimise the impact on Defence users.

