The HMAS Adelaide will also join ships already mobilised to evacuate people from fire-affected areas.

The Commonwealth has also committed up to $20 million to lease four extra aircraft for the firefighting effort.

It is the first time in Australia's history that a Call-Out of Australian Defence Force Reserve Brigades has been made.

Speaking to media at Parliament House, Mr Morrison said the Governor General had "signed off on the call-out of the Australian Defence Force Reserve to search and bring every possible capability to bear by deploying army brigades to fire affected communities across Australia."

"A two-star emergency ADF national support co-ordinator will have national authority over the ADF joint taskforces in each of the affected states working in co-operation to support state emergency authorities," he said.

Two ADF taskforces have been established in New South Wales and Victoria and a third will be stood up for South Australia, with a focus on Kangaroo Island, Mr Morrison said.

"The priority of this deployment is to assist in ensuring the safety of life, to support the evacuation of affected people, particularly in isolated communities and to provide assistance to isolated communities and support state-managed evacuation centres."

The Prime Minister announced Chinook helicopters, C-17 Globemasters, C-130 Hercules and C-27 Spartans would also join the effort.

The ADF surge includes the deployment of up to 3,000 designated ADF Reserve forces including the 4th Brigade from Victoria, the 5th Brigade from New South Wales, and the 9th Brigade from South Australia and Tasmania and specialist logistic elements of the 17th Brigade headquartered in New South Wales to push Defence resources into fire-affected areas progressively, and in coordination with State authorities, from as early as tomorrow.

These Brigades will be enhanced with specialist ADF personnel with skills in engineering, medical, logistics and transport support.