(CNN) -- Germany's justice minister has asked the UK government whether German citizens have been affected by mass surveillance programs reportedly carried out by UK and U.S. authorities.
Germany needs "a swift clarification of the facts and transparency on reported mass surveillance," German Justice Minister Sabine Leutheusser-Schnarrenberger said in a statement.
"The German Government wants to know whether and to which extent the communication of especially German and European citizens has been and still is affected by British and American surveillance programs."
She has written to her UK counterpart, Justice Secretary Chris Grayling, and Home Secretary Theresa May, a spokesman for the German Justice Ministry said Wednesday.
A UK Ministry of Justice spokeswoman said it would respond to the letter "in due course." The UK Home Office said it did not comment on private correspondence.
The German government's concern follows allegations in The Guardian newspaper on Friday that the UK equivalent to the U.S. National Security Agency, the Government Communications Headquarters, has tapped into many of the world's key international fiber-optic cables and is routinely downloading and analyzing vast quantities of Internet and phone traffic, sharing the data with the NSA.
The Guardian said its report was based on the reading of documents provided by former U.S. defense contractor Edward Snowden, who admitted leaking documents this month detailing government surveillance programs.
The NSA dismissed that report as "absolutely false," and a GCHQ spokesman said it declined to comment on intelligence matters, in line with long-standing practice.
The allegations have prompted wide public concern in the United Kingdom and United States.
But Leutheusser-Schnarrenberger's statement highlights a broader unease within Europe over the extent of the reported surveillance programs.
"The internet offers great opportunities -- for our citizens' participation and communication, for our economies and for the protection of human rights in general," she said.
"But our citizens need to have trust into the new form of communication. Mass surveillance and treating every citizen as potentially suspicious undermines this trust."
The retention of all communications data without any evidence goes against the German Constitution, she said, while increased data protection is "not an obstacle to an effective fight against terrorism or any other crimes."
UK Foreign Secretary William Hague defended UK-U.S. operations in a speech given Tuesday at the Reagan Presidential Library in California, saying that in both countries, a "strong legal framework" governs intelligence work.
"We should have nothing but pride in the unique and indispensable intelligence-sharing relationship between Britain and the United States," he said.
"We operate under the rule of law and are accountable for it. In some countries, secret intelligence is used to control their people. In ours, it only exists to protect their freedoms.
"We should always remember that terrorists plan to harm us in secret, criminal networks plan to steal from us in secret, foreign intelligence agencies plot to spy on us in secret, and new weapons systems are devised in secret. So we cannot protect the people of our countries without devising some of the response to those threats in secret."
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