President Barack Obama on Wednesday defended US Internet and phone surveillance programmes which sparked alarm in Europe, saying American spies were not "rifling" through the emails of German and French citizens.
Obama insisted that the programmes run by the super secret US eavesdropping service the National Security Agency (NSA) were legal and limited and were a vital tool in the fight against global terrorism.
"This is not a situation where we are rifling through, you know, the ordinary emails of German citizens or American citizens or French citizens or anyone else," Obama said after meeting German Chancellor Angela Merkel.
Obama argued that "lives have been saved" because of the use of the surveillance system, including in Germany, where memories of communist Stasi secret police eavesdropping still linger.
"We know of at least 50 threats that have been averted -- not just in the United States, but in countries around the world, including Germany," he told a joint news conference with Merkel.
Obama said a balance must be struck between ensuring the security of citizens and protecting their privacy.
He offered a long explanation to Germans about the controversial programmes, which he said involved sweeping up data on phone and Internet traffic, but not delving into the specific content of the calls.
Only if there are leads related to terrorism or the proliferation of weapons of mass destruction, would US agents ask a special court to allow them to look deeper into the records, he said.
Merkel told reporters that the Internet was "new territory" for everyone and offered new possibilities to be abused by "enemies and opponents" but urged the need for "proportionality".
Germany values the security cooperation with the US, which had led to an important tip-off to Germany on an Islamist cell, she said. But she added: "I also made it clear... that the theme of proportionality is always an important theme."
Merkel, who grew up in communist East Germany, said basic freedoms depended on people being able to feel safe "and therefore the question of balance, the question of proportionality, is something that we will further discuss with one another".