SCHULD/ERFTSTADT, Germany, July 16 (Reuters) - German officials feared more deaths on Friday after "catastrophic" floods swept through western regions, demolishing streets and houses, killing more than 100 people and leaving hundreds more missing and homeless.

Communications were cut in many areas and entire communities lay in ruins after swollen rivers tore through towns and villages in the western states of North Rhine-Westphalia and Rhineland-Palatinate as well as parts of Belgium and the Netherlands.

After days of heavy rain, 103 people have died in Germany alone, the largest number killed in a natural disaster in the country in almost 60 years. They included 12 residents of a home for disabled people surprised by the floods during the night.

In Belgium, which has declared a day of mourning on Tuesday, officials said there were at least 20 dead and another 20 missing.

The flooding was a "catastrophe of historic dimensions," said Armin Laschet, state premier of North Rhine-Westphalia and the ruling CDU party's candidate to replace Chancellor Angela Merkel when she steps down after an election in September.