The Royal Australian Navy’s largest vessel has set sail from Sydney to help support firefighting efforts as the Australian Defence Force ramps up its role in the bushfire crisis.

The HMAS Adelaide will be stationed off the country’s east coast, along the New South Wales-Victorian border, and is expected to arrive tomorrow morning.

HMAS Adelaide's deployment is part of additional ADF assistance announced by Prime Minister Scott Morrison which also involves the compulsary call up of up to 3,000 army reservists.

Saturday’s announcement marked the first time in Australia's history a compulsory call out of reservists has been issued.

HMAS Adelaide is the navy's largest amphibious ship and carries purpose-built water craft that can transport people to and from the shore, even where there are no ports.

It will join HMAS Choules and MV Sycamore working to evacuate residents trapped in coastal towns cut off by bushfires.

Able seaman and Nowra resident Kellie Cully will be stationed in the same area of the country she calls home.

She said news of the deployment came “very quick” and her local knowledge would be “vital”.

“It's really exciting. I'm happy. I'm honoured to go help the people in my area along the south coast of New South Wales,” she said.

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“[I will] know where to go and where the evacuation centres are.

“[I can] also help out people who are not from the area [by] telling them where to go and where the safest places [are].”

Able Seaman Alex Rudd is from the NSW coastal town of Ulladulla.

"It's terrifying [but] going down is a great honour and a privilege,” he said.

“I'm very glad to be a part of assisting with the fires where I can.”

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In addition to the extra ship, Mr Morrison announced extra firefighting planes would be leased to join the national bushfire efforts at a cost of $20 million.

Australian Defence Force bases from Brisbane to Adelaide will also be opened up to house people effected by the bushfires in need of accommodation.