The Danube River has risen to its highest level in more than two decades, driving people from their homes in Serbia and causing alarm in neighboring Bulgaria and Romania.

The Serbian government has introduced emergency measures to cope with floods along the Danube and its tributaries the Tisa, the Tamisa and the Sava Rivers. Waters from torrential rains and melting snow threaten Serbia's capital Belgrade.

Serbian officials say more than 1,000 troops, firefighters and emergency personnel are placing sandbags in critical zones along river banks to ease the situation in Belgrade and northern Serbia. Bulgaria and Romania are taking similar measures to prepare for floods.

Officials say the water levels are expected to persist for at least four more days.

Some information for this report was provided by Reuters.