The death toll from flooding triggered by heavy rainfall in western and southern Germany has risen to more than 100 as of Friday noon local time, according to police and local authorities.

Deaths related to the extreme weather were also reported in neighboring Belgium, where at least nine people have died, while Luxembourg and the Netherlands have also been severely affected by the torrents of water, with thousands evacuated in the city of Maastricht.

In the badly-hit western German state of Rhineland-Palatinate, at least 50 deaths were reported and local authorities feared more fatalities were likely as media reports suggested around 1,300 people were still unaccounted for in the region. 

Official mourning for the victims will take place on Friday, with all public flags set to fly at half-mast across the state.

In another German state, North Rhine-Westphalia, officials earlier announced that at least 30 people had died as a result of the natural disaster.

Local media warned a dam bridge in the area may collapse and officials have urged people to help each other.

"I fear that we will only see the full extent of the disaster in the coming days," German Chancellor Angela Merkel said late Thursday during a visit to Washington.

(With input from agencies)