Kevin Rudd says Scott Morrison is unfit to occupy Australia's highest office after the Prime Minister released a promotional Liberal Party video spruiking his response to the bushfire crisis, which has been the subject of fierce criticism.

The Prime Minister released the video on social media on Saturday evening as catastrophic conditions again hit New South Wales and Victoria and the mercury neared 50 degrees celsius in Penrith, western Sydney. Earlier in the day, Mr Morrison and Defence Minister Linda Reynolds had announced an unprecedented deployment of the military across the fire grounds.

The video is set to an upbeat musical backing track and features shots of the Prime Minister visiting fire-ravaged areas. The images are in stark contrast to the visit in which Mr Morrison was heckled by locals in Cobargo, on the NSW South Coast.

The 50 second-clip has been watched more than 1.3 million times on Twitter alone but many viewers have taken exception to the video, which ends with the Liberal party's disclaimer "authorised by S Morrison, Liberal Party, Canberra".