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Hundreds of demonstrators protest against the supposed surveillance by the US National Security Agency, NSA, during a rally in in Berlin, Germany, Saturday July 27, 2013. (AP Photo/dpa, Wolfgang Kumm)

BERLIN -- Thousands of people are taking to the streets in Germany to protest against the alleged widespread surveillance of Internet users by U.S. intelligence services.

Protesters, responding to calls by a loose network calling itself #stopwatchingus, braved searing summer temperatures Saturday to demonstrate in Hamburg, Munich, Berlin and up to 35 other German cities and towns.

Some wore tinfoil hats to shield themselves from the sun -- and make a political statement about warding off unwanted eavesdroppers.

Others held placards showing support for National Security Agency leaker Edward Snowden.

Chancellor Angela Merkel raised the issue of the NSA's alleged interception of Web traffic when U.S. President Barack Obama visited Berlin last month. But German opposition parties remain skeptical of the government's claim that it had known nothing about the surveillance.