Moody's rating agency has downgraded seven banks in Germany, citing risks from the eurozone debt crisis and prospects of weaker global economic growth.

The most prominent bank downgraded late Tuesday night was Commerzbank AG, Germany's second-biggest. Its long-term rating was cut to A3, with a negative outlook, from A2.

Also hit were DekaBank and DZ Bank, as well as three of Germany's public-sector regional banks — Landesbank Baden-Wuerttemberg, Norddeutsche Landesbank and Landesbank Hessen-Thueringen.

The German unit of Italy's UniCredit was downgraded to A3, with a negative outlook, from A2.

Moody's said its move was driven in part by "the increased risk of further shocks emanating from the euro area debt crisis in combination with the banks' limited loss-absorption capacity."

Germany's economy, Europe's biggest, remains robust as other eurozone countries struggle.