Floodwaters slowly receded in the Balkans on Thursday after the region's deadliest natural disaster in living memory, revealing widespread devastation and allowing the mammoth cleanup task to begin.

The first evacuees got a green light to return home, among the 150,000 who fled as the Sava river burst its banks and laid waste to parts of Bosnia, Serbia and Croatia.

The death toll from the Balkans' worst floods in more than a century stands at 51, but more bodies could be found in houses and farms swamped by the floods and landslides.

Vast tracts of farmland remain under muddy brown water, large areas are without power and many places are difficult to access. Returning residents have been greeted by scenes of desolation and an unbearable stench.

"We need international aid. In this first phase alone, people need clothes and food," said Igor Radojicic, parliamentary speaker in the Bosnian Serb entity Republika Srpska.

"Lots of people are not going to have a home anymore."

The past week's floods affected more than 1.6 million people across the Balkans, with a quarter of Bosnia's population of 3.8 million without safe drinking water.

In Croatia, which escaped the worst damage, authorities said 38,000 people have been affected by the floods, with some 2,000 houses and 199 farms destroyed.

With temperatures approaching 30 C, a major challenge remains clearing up drowned animals before their carcasses start to rot in the heat and potentially spread disease.

In Serbia, around 200 metric tons of dead animals have been recovered, the agriculture ministry said. Health officials were also spraying to try to prevent a plague of mosquitoes.

Dislodged landmines

Complicating the operation in Bosnia is the danger that the floods and landslides could have dislodged some of the 120,000 potentially deadly landmines left over from the Yugoslav wars of the 1990s.

On Tuesday, one such device exploded in northern Bosnia, the national Mine Action Center said, although no one was injured. A fridge full of explosives and a rocket-launcher thought to date from the conflict were also recovered.

"Some mines are made of plastic and they float like plastic plates," said Fikret Smajis from the mine center. "But even those made of iron ... can be easily washed away."

Visiting NATO chief Anders Fogh Rasmussen said in Sarajevo on Wednesday that the members of the military alliance "remain ready to respond in any way that would be needed".

Meanwhile, Serbia's Prime Minister Aleksandar Vucic was due to meet with officials from the World Bank, the European Bank for Reconstruction and Development and the United Nations to seek financial help.

Vucic has said that with hundreds of bridges damaged and 3,500 km of roads needing repairs, the total bill could be as high as one billion euros ($1.4 billion).

In Bosnia, officials have estimated the bill could be hundreds of millions of euros, while in Croatia damage to agriculture alone is expected to reach at least 30 million euros.

A woman reacts near her house in Topcic Polje, on Tuesday. At least 40 people have died in Serbia, Bosnia and Croatia, after days of the heaviest rainfall in recent 120 years caused rivers to burst their banks and triggered hundreds of landslides. Dado Ruvic / Reuters

(China Daily 05/23/2014 page11)