Australia is bracing for days of “catastrophic” fire and heatwave conditions, with fires burning in five states and a search continuing for people missing after devastating wildfires in the island state of Tasmania.

Julia Gillard, the Australian prime minister, toured fire-ravaged Tasmanian townships and promised emergency aid for survivors, who told of a fireball that engulfed communities across the thinly populated state on Friday and Saturday.

"The trees just exploded," local resident Ashley Zanol told Australian radio, recounting a wall of flames that surrounded his truck as he carted water to assist fire crews in the township of Murdunna, which was largely destroyed.

Tasmanian police said around 100 people feared missing in bushfires had been accounted for and there had so far been no deaths as authorities combed through smouldering ruins of homes and vehicles while evacuating local people and tourists.

Australian authorities search burnt-out homes in Tasmania. Link to this video.

There are fires in five of Australia's six states, with 90 in the most populous state of New South Wales and in mountain forests around the national capital, Canberra.

Severe fire conditions were forecast for Tuesday, replicating those of 2009, when the Black Saturday wildfires in Victoria state killed 173 people and caused $4.4bn-worth (£2.7bn) of damage. Guardian News Service