Tourists walk past burned cars on Wednesday at a campsite near Peschici, Italy, a day after a fire roared through the area, killing four people. ((Gregorio Borgia/Associated Press))

Health officials in Hungary blamed extreme temperatures for the deaths of 500 sick or elderly people, as southeastern Europe continued to roast under a record-breaking heat wave Wednesday.

Temperatures that reached a historic 41.9 C in parts of Hungary may have aggravated heart and breathing problems and caused heatstroke, said the country's chief medical officer, Dr. Ferenc Falus.

From July 15 to 22 in central Hungary, the heat "contributed to the premature deaths of 230 people — which means 500 extra deaths at the national level," Falus said from Budapest.

The heat wave, the second to hit southern Europe in a month, has set record temperatures in many areas, including Belgrade — which saw a stifling 43 C, the highest ever recorded — and Bulgaria, which reached a record-breaking 44 C.

Some countries, including Romania, Greece and Hungary, were expecting temperatures to climb past 40 C again on Wednesday.

In Italy, fleets of firefighters were struggling to cope with dozens of wildfires amid the dry conditions and an onslaught of heat-related emergency calls. Acres of forest in the south and central Italy were destroyed.

Responding to complaints of slow rescue efforts and response times, Italy's civil defence department said the situation was "unprecedented" but that its emergency resources were already working at full capacity.

Macedonia orders army to help fight fires

Meanwhile, Romania's government said Wednesday that, since the previous week, at least 27 deaths have been attributed to the heat in the country, where forest fires destroyed dozens of homes. All the victims were over 70 and had not taken proper care to cool themselves such as stay hydrated or wear a hat, Health Minister Eugen Nicolaescu said.

Heavy energy consumption in Bucharest caused power outages in the Romanian capital as residents blasted air-conditioning to escape the weather. Romanian Finance Minister Varujan Vosganian said energy use had surged by more than 50 per cent.

Macedonia's president declared a national emergency asCroatia, Turkey and Austria flew army units and water-bombers to Macedonia to help douse forest fires.

One person died in Macedonia onTuesday as hundreds fled a large fire in the country's second-largest city, Bitola. The fires in the city were under control by Wednesday, but had not been fully extinguished.

The Greek government was also on high alert and Athens was expected to swelter in 45 C temperatures.

With files from the Associated Press