Chancellor Olaf Scholz on Saturday toured rain-hit regions of south-west Germany, where rivers have swelled and caused flash floods and landslides.
A huge downpour on Friday in the German state of Saarland deluged buildings, left streets deep underwater and sparked evacuations, with rescuers carrying stranded residents to safety in boats.
German emergency workers were on Saturday starting a major clean-up operation.
Officials said it was the worst flooding in the area in nearly 30 years, with the capital Saarbrücken badly affected and reports saying that a breach in a dyke led to a power station in the state being shut down.
No deaths were reported but at least one person was injured.