Germany's top justice official said reports that US intelligence bugged European Union offices remind her of "the methods used by enemies during the Cold War".
Justice Minister Sabine Leutheusser-Schnarrenberger was responding to a report by German news weekly Der Spiegel that claimed the National Security Agency (NSA) has eavesdropped on EU offices in Washington, New York and Brussels.
The magazine cited classified US documents taken by former NSA contractor Edward Snowden that it said it had partly seen.
The documents reportedly describe the European Union as a "target" for surveillance.
Ms Leutheusser-Schnarrenberger said it was "beyond comprehension that our friends in the United States see Europeans as enemies".
She called for an "immediate and comprehensive" response from the US government to the claims.
