Torrential rain has worsened flooding along the River Danube in parts of Romania and Bulgaria, where thousands of people have fled their homes.
Some streets in Nikopol, Bulgaria, are navigable only by boat
Both countries are battling to bolster dykes weakened by the swollen river, with the Bulgarian ports of Vidin and Nikopol among the towns most at risk.
Thousands of homes and a vast area of farmland have been damaged.
Heavy rainfall and melting snow have pushed the Danube to its highest level for more than a century.
Officials in Romania and Serbia say the volume of water flowing through has receded slightly over the past few days.
According to the Romanian environment ministry, Danube water flow near the Romanian-Serbian border fell to 15,200 cubic metres per second, having hit an 111-year high of 15,800 on Saturday.
However, thousands of evacuated people remain in temporary shelters and a full estimate has yet to be made of the damage to farmland and homes.
Constantin Raicea, mayor of the Romanian village of Bistret, told the Reuters news agency some 200 houses could be flooded "if water breaks the dykes, but with the help of God this won't happen".
He said military helicopters will be used to drop bundles of reed to bolster dykes.
'Nowhere to go'
Some of the heaviest rainfall on Thursday was reported in north-western Bulgaria's Vratsa district.
Roads and bridges in the region were damaged and the lower floors of houses in the villages of Vladimirovo and Banitsa were flooded, the Associated Press reported.
More than half the houses bordering the Danube in the Bulgarian port of Nikopol were reported to be flooded.
In another Bulgarian port town, Vidin, workers raced to strengthen weakened dykes.
Some 4,000 people from the village of Rast in south-western Romania have been staying in schools, hospitals or the houses of relatives in higher areas.
The village has been submerged since a dyke collapsed on Sunday.
Romania's interior ministry has prepared packages containing eggs, lamb and cake for some of the displaced villagers, who have little hope of returning home to celebrate the Orthodox Christian Easter.
"Life is a curse. Floods are a curse and God is angry now on the eve of Easter," one of the villagers, 60-year-old Gherghita Garleanu, told Reuters. "I have nowhere to go back to after the water recedes," she said.
Flooding in the Balkans last year killed dozens of people and destroyed huge swathes of farmland.
Economic losses from this year's floods are not thought to be as high as they were last year or in 2002, when large areas of Central Europe were submerged by swollen river waters.
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