SYDNEY, Jan 31 (Reuters) - A heatwave blamed for raging bushfires and a spate of deaths eased a little in Australia's densely populated southeast on Saturday, but a ban on lighting fires in the open remained in force.

Temperatures slipped below 40 degrees Celsius in most major centres for the first time in several days, but parts of Melbourne and Adelaide still recorded temperatures above that mark.

Authorities fear several elderly people may have died due to the heatwave, after 22 "sudden deaths" in Adelaide on Friday.

Sudden deaths are those caused by medical conditions such as heart attacks and strokes, said an ambulance official, adding autopsies would determine whether the deaths were heat-related.

In Melbourne, power was largely restored after blackouts left hundreds of thousands of homes in the dark on Friday, but a major bushfire was still burning in the east of Victoria state.

A spokesman for the state's Country Fire Authority said the fire had destroyed 15 homes, consumed 6,000 hectares and was just two kilometres away from a major power line. However, fires elsewhere in the state had largely been brought under control.

Authorities believe some of the fires were started deliberately and have maintained daily 'fire bans' for most areas, under which it is illegal to start a fire.

Australia's Bureau of Meteorology forecast temperatures below 40 degrees Celsius for Sunday for most centres, although it said Adelaide could hit a maximum of 40 degrees.

(Editing by Sanjeev Miglani)

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