Concern is centered on the village of Bistret, where a dike cracked earlier on April 18.
Several thousand people have fled their homes and some 40,000 hectares of land have been flooded in Romania in recent days as the river reached its highest level in more than a century.
Water levels were expected to continue to rise through April 19 both in Romania and in neighbouring Bulgaria. However, the waters should recede slightly in Serbia.
(compiled from agency reports)