Germany said on Monday if media reports of large-scale U.S. spying on the European Union were confirmed, it would be unacceptable Cold War-style behaviour between partners who require trust to forge a new transatlantic trade area.
"If it is confirmed that diplomatic representations of the European Union and individual European countries have been spied upon, we will clearly say that bugging friends is unacceptable," said Chancellor Angela Merkel's spokesman, Steffen Seibert.
"We are no longer in the Cold War," he said.
Berlin felt surprised and "alienated" by the reports and had conveyed this to the White House and Merkel would speak to U.S. President Barack Obama directly about the issue soon, he said.
Fury among America's allies over former U.S. spy agency contractor Edward Snowden's revelations of secret surveillance programmes were exacerbated this weekend by a German magazine report that the NSA had tapped communications at EU offices in Washington, Brussels and at the United Nations.
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U.S. Secretary of State John Kerry said most governments use "lots of activities" to defend their interests.
According to Der Spiegel, the NSA taps half a billion phone calls, emails and text messages in Germany in a typical month, much more than any other European peer.
The European Union has demanded an explanation and Germany's Foreign Ministry has summoned the U.S. ambassador to discuss the revelations later on Monday, officials said.
EU politicians say talks between Brussels and Washington about creating the world's biggest free-trade area could even be at risk. Germany wants such a deal, which would foster growth and job creation on both sides of the Atlantic, Seibert said.
But he added that "mutual trust is necessary in order to come to an agreement. We must negotiate on the agreement in an atmosphere of trust and on a level playing field and that is the atmosphere that needs to be created."
Seibert brushed aside a suggestion by the opposition Greens that the EU should provide a safe haven for Snowden.
Juergen Trittin, parliamentary leader of Germany's third biggest party, said 30-year-old Snowden "should get safe haven here in Europe because he has done us a service by revealing a massive attack on European citizens and companies."
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