Sydney  - Melbourne residents braced for another week of extreme heat Sunday as officials copped criticism for failing infrastructure and an unofficial death toll as high as 30.

Those who succumbed to the intense heat were all over 70 and had pre-existing medical conditions.

The 3.8 million people of Australia's second-biggest city last week endured the hottest spell since 1855 and their worst power failures ever.

The state government of Victoria defended its efforts against claims it was unprepared for four days of above 40-degree heat.

"It's a once-in-a-hundred-year event with record temperatures," Education Minister Bronwyn Pike said. "But what we've been doing as a government is getting out there and standing alongside people, doing everything we possibly can to help them cope."

Melbourne, which recorded its hottest day since 1939 on Friday, with a top temperature of 45 degrees, is bracing for mid-30s temperatures all this week.

Fires elsewhere in the state of Victoria claimed 29 homes and scorched 7,000 hectares. Volunteer firefighters aboard more than 100 fire engines were tackling the blazes, backed by water-bombing aircraft. dpa