Up to 3,000 army reservists and an extra naval ship will join bushfire disaster and recovery efforts.

Prime Minister Scott Morrison announced the extra bushfire assistance on Saturday afternoon as fire conditions deteriorate across Australia's south east.

Four extra firefighting planes would also be leased to join 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.

Supplied: ADF

"The issue that is needed today is boots on the ground, planes in the air, ships at sea and trucks rolling into communities that have been impacted," Mr Morrison told reporters in Canberra on Saturday.

HMAS Adelaide would leave Sydney on Saturday to help with coastal evacuations at the NSW and Victorian border.

Defence is poised to set up a national task force to coordinate personnel involved in bushfire assistance across the country.

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