In Romania, the heat wave's death toll rose to 30 and 19,000 people had been admitted to hospital in the region's second devastating hot spell this year.

Bucharest tried to cope with sporadic power blackouts under an increased load of air conditioners and fans, but health officials were able to cancel "Code Red" emergency measures declared on Monday as they forecast easing temperatures.

"We have good news ... from Thursday we will shift to 'Code Green'," Health Minister Eugen Nicolaescu told reporters.

More than 35 people died in Romania, Turkey and Greece in June when the mercury shot up to 46 Celsius.

Forests in Bosnia, Serbia, Montenegro and Macedonia, Bulgaria and Greece have been ravaged by flames this week, blamed on record-high temperatures after the dry winter.

"I spoke with the Greeks and the Bulgarians to ask for help, but they have the same problem," said Predrag Maric, chief of Serbia's police rescue department.

"We hoped a Russian water-bomber would arrive in the morning, but they had to go help in Bulgaria where the situation is critical. And today will be the hottest day of the year."

In Macedonia temperatures were expected to hit an all-time record of 45 degrees Celsius during the day. One man died of smoke inhalation overnight in the southern town of Bitola and 200 were evacuated from a suburb.

In Bosnia, the southern towns of Citluk, the Adriatic port of Neum and the mountain town of Visegrad declared states of emergency. Towns and villages faced power cuts and water shortages due to the fires.

"The wind is our biggest enemy, it speeds up the burn enormously," said Stanko Sliskovic, Civil Defence Secretary of Bosnia's Muslim-Croat federation.

There were 18 fires burning in Serbia's breakaway Kosovo province, most near inhabited areas including the capital Pristina, and police, forestry officials and soldiers from the resident NATO-led peacekeeping force KFOR were battling flames.