(SOURCE) Water levels on the River Sava are expected to peak later, threatening the country’s biggest power plant.
It comes after the worst floods in the Balkans for decades left at least 20 dead and forced tens of thousands of people to flee their homes.
In Bosnia-Hercegovina, landslides have buried houses and disturbed landmines laid during the war in the 1990s.
The floods are also affecting Croatia.
Three months’ worth of rain fell on the region in just a few days, causing rivers to burst their banks and sweep into people’s homes. The death toll is expected to rise.
Flood alerts are still in place in many areas of Serbia and northern Bosnia, according to the EU Floods Directive.
The rain has finally stopped in Belgrade, reports the BBC’s Guy De Launey in the Serbian capital.
But officials fear water flowing from neighbouring Croatia and Bosnia could cause a “flood wave” on the River Sava on Sunday evening.
Emergency workers and volunteers have stacked sandbags along the river in Belgrade and other towns such as Sabac and Sremska Mitrovica.