If it were disclosed that diplomatic facilities were being used to do spying, "serious harm" could be done to relations with host countries, Der Spiegel reported one document as saying. But the magazine said it was not clear from the leaked documents whether intelligence agencies had been listening to Merkel's conversations or whether they had simply been collecting connection data.
The allegations over spying have created an uproar in Europe, especially in Germany, where furious officials have said that they feel as if U.S. spy agencies have treated them as untrustworthy enemies instead of as being among America's staunchest allies. Merkel said last week that she would press for clear guidelines about what U.S. intelligence agencies were permitted to do on German soil.
Friedrich was quoted Sunday as saying that he wants legal consequences if crimes have been committed.
"If the Americans eavesdropped on cellphones in Germany, they broke German law on German soil," Friedrich said, according to the newspaper Bild am Sonntag. "Eavesdropping is a crime and those responsible must be held accountable."
German news reports Sunday offered contrasting accounts of when President Barack Obama might have known of any spying. In a conversation Wednesday between Obama and Merkel, he told her that he had not known that her cellphone had been monitored, the German newspaper Frankfurter Allgemeine Sonntagszeitung reported Sunday, without citing its source. But Bild am Sonntag, citing an unnamed NSA official, reported Sunday that Gen. Keith Alexander, director of the NSA, had informed Obama of the monitoring in 2010.