A man walks through flood water in the town of Obrenovac, near Belgrade, May 18, 2014. Soldiers, police and villagers battled to protect power plants in Serbia from rising flood waters on Sunday as the death toll from the Balkan region's worst rainfall in more than a century reached 37. Twelve bodies were recovered from the worst-hit Serbian town of Obrenovac, but the number was likely to rise as waters receded. [Photo/Agencies]

KOSTOLAC, Serbia/DOBOJ, Bosnia - Soldiers, police and villagers battled to protect power plants in Serbia from rising flood waters on Sunday as the death toll from the Balkan region's worst rainfall in more than a century reached 37.

Twelve bodies were recovered from the worst-hit Serbian town of Obrenovac, 30 km (18 miles) southwest of the capital, Belgrade, but the number was likely to rise as waters receded.

Bodies pulled from submerged homes in Balkans flooding

"The situation is catastrophic," Prime Minister Aleksandar Vucic told reporters.

Hundreds of soldiers and residents scrambled to raise sandbag barriers around the perimeter of the Kostolac power plant east of Belgrade, where waters from the swollen River Mlava, a tributary to the much larger River Danube, had come to within a kilometre.

Workers at the plant joined the effort, digging up a road in a bid to divert waters that threatened to flood nearby coal mines. The Kostolac plant supplies 20 percent of Serbia's electricity needs.

Russian cargo planes carrying boats, generators and food joined rescue teams from around Europe and thousands of local volunteers in evacuating people and building flood defences after the River Sava, swollen by days of torrential rain, burst its banks.

Rains eased and flood waters receded on Sunday in some of the worst-hit areas of Serbia and Bosnia, but the Sava was forecast to rise further. Thousands of people have been displaced.

Serbia's EPS power utility said a fresh flood wave also threatened Serbia's largest power plant, the Nikola Tesla in Obrenovac.

Flooding had already cut Serbian power generation by 40 percent, forcing the cash-strapped country to boost imports.

"More and more water is getting closer but for the time being the sandbag defence barriers are holding," Tanjug news agency quoted Kostolac general manager Dragan Jovanovic as saying.