German security agents recorded a conversation involving Hillary Rodham Clinton while she was U.S. secretary of state, media reported Friday, a potential embarrassment for Berlin which has lambasted Washington for its widespread surveillance.

Clinton's words were intercepted while she was on a U.S. government plane, Germany's Sueddeutsche Zeitung newspaper and German regional public broadcasters NDR and WDR said, without giving details of where she was or when the recording was made.

The respected broadsheet quoted German government sources as saying the conversation had been picked up "by accident" and was not part of any plan to spy on Washington's former top diplomat. The fact the recording had not been destroyed immediately was "idiocy," said one of the sources.