Work is continuing for the sixth consecutive day to build and reinforce flood barriers in Hungary as the River Danube reaches record heights.
Low-lying northern areas of the capital are particularly at risk, but the threat extends along 200km of the river.
A BBC correspondent says there is a sense of siege in Budapest.
Heavy rain is hampering the repair work on sandbag and earth walls.
Mayor Istvan Tarlos said up to 55,000 people may need to be evacuated in the worst-case scenario.
However, he said he was confident that only the lowest-lying areas would be exposed to the river's expanded flow.
About 2000 people were moved late on Friday from Gyorujfalu near the city of Gyor, because a dyke weakened after a landslide.
Some small towns and villages are cut off and river levels are expected to peak in Budapest on Monday.
Forecasters say levels could rise to 8.85m - about 25cm higher than the Danube's previous record height in 2006.
in Germany, vast areas around the city of Magdeburg are covered in a sea of brown water which have washed down the Elbe river system from the Czech Republic.
