DUESSELDORF, Jan 9 (Reuters) - The German department store giant Galeria Karstadt Kaufhof said on Tuesday that it filed for insolvency, as the fallout of a real-estate crisis in the region widens.

Galeria, the nation's most prominent retailer, is owned by Signa, the insolvent Austrian-based property empire that has become the biggest casualty so far in Europe's real-estate crisis. (Reporting by Matthias Inverardi and Tom Sims, Editing by Rachel More)