Four under-performing government departments will be subsumed into four new "mega-departments", and their public servant chiefs axed, under a massive bureaucratic shakeup announced by the prime minister on Thursday.

Effective from February 1 next year, the number of federal government departments will be slashed from 18 to 14.

Watch the video above

Scott Morrison said the new structure would "ensure that services that Australians rely on are delivered more efficiently and more effectively".

New departments

Education, Skills and Employment - a merger of the Department of Education and the Department of Employment, Skills, Small and Family Business, leaving the department's secretary, Kerri Hartland, without a job

- a merger of the Department of Education and the Department of Employment, Skills, Small and Family Business, leaving the department's secretary, Kerri Hartland, without a job Agriculture, Water and the Environment - consolidating the Department of Agriculture and removing its secretary Daryl Quinlivan, and taking over the environment functions from the current Department of Environment and Energy

- consolidating the Department of Agriculture and removing its secretary Daryl Quinlivan, and taking over the environment functions from the current Department of Environment and Energy Industry, Science, Energy and Resources - which will take over the energy functions from the current Department of the Environment and Energy and the small business functions from the Department of Employment, Skills, Small and Family Business

- which will take over the energy functions from the current Department of the Environment and Energy and the small business functions from the Department of Employment, Skills, Small and Family Business Infrastructure, Transport, Regional Development and Communications - effectively axing the Department of Communications and the Arts, along with its bosses Mike Mrdak and Heather Smith.

The Department most Australians know as Human Services, now called Services Australia, will be subsumed into the Social Services Department, making Renee Leon redundant.

Morrison said the shakeup was not about saving money.

Breaking down silos

Instead, the changes would "bust bureaucratic congestion ... and break down silos", he said in a press conference in Canberra, issues that were identified in the recent Thodey review of the public service.

The review handed down its final report to the government in September, a few weeks after Morrison flagged his intention to shake up the public service, saying it needed to "evolve" and in some cases "conventional wisdom needs to be challenged".

More on 7NEWS.com.au

He placed the blame of public servant disengagement squarely at the feet of senior management, warning that he expected public service leaders to change their style.

Labor deputy leader Richard Marles told Sky News on Thursday that stability in the public service was vital.

"I think it's really important - particularly at this time, given all the challenges that we're facing - that the government is managing the public service in a way which maintains stability and ultimately maintains morale," he said.

Your cookie settings are preventing this third party content from displaying. If you’d like to view this content, please adjust your Cookie Settings . To find out more about how we use cookies, please see our Cookie Guide.

- with AAP