An arrest warrant was issued Thursday for an Australian-trained doctor who appeared in an Islamic State propaganda video which urges other medical professionals to join the jihadists, police said.

Tareq Kamleh was shown in the slick video, uploaded to YouTube in April, identifying himself as Abu Yusuf and explaining that he traveled to the city of Raqa in Syria to use his medical skills in the IS cause.

Firefighters battled Monday to contain a major blaze ahead of the forecast return of strong winds and a heatwave following the loss of a dozen homes in the worst bushfire conditions in South Australia for three decades, officials said.

The state fire service said properties were still at risk after nearly 13,000 hectares of scrub and farmland were razed in the Mount Lofty Ranges, east of Adelaide, over the weekend.

Skies over southeastern Australia darkened with huge plumes of smoke and lightning storms Friday after an epic heatwave, with raging wildfires claiming one life and residents warned to "leave and live".

A cool change began sweeping the states of South Australia and Victoria as evening fell, bringing much-needed relief to millions of residents who have sweltered through up to five days of scorching temperatures in excess of 40 degrees Celsius (104 Fahrenheit).

U.S. singer Cher is "upset" and trying to get to the bottom of why a key to the city of Adelaide she was given in 1990 ended up on eBay, selling Thursday for nearly US$100,000.

The appearance of the brass key and an accompanying memorial plaque on the Internet auction house offended officials in the southern Australian city, with Adelaide mayor Stephen Yarwood saying he was "exceptionally disappointed."