German Chancellor Angela Merkel has called for answers over "grave" US spying accusations which she said were testing transatlantic ties, including fledgling trade talks.
Ahead of a special debate on snooping by US intelligence on German soil which included the suspected tapping of her mobile phone, Merkel addressed the US espionage claims at the start of a speech to parliament.
"The transatlantic relationship and therefore also the negotiations for a free-trade agreement are presently without doubt being put to the test by the remaining accusations against the US and the million-fold collection of data," Merkel told the Bundestag lower house.
"The accusations are grave. They must be explained and, more important still for the future, new trust must be built," she said to applause.
Merkel, who went on to speak about EU partnerships with Eastern European countries, did not directly mention the surveillance of her phone.
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But she stressed that the relationship with the United States was of "paramount" importance for Germany and Europe, and the "common experiences, values and interests" shared by Berlin and Washington DC.
With US President Barack Obama's June visit to Berlin still fresh in many minds, lawmakers called a special parliamentary debate on the revelations that have put the US in the firing line and strained diplomatic ties, also clouding EU-US talks on what would be the world's biggest free-trade accord.
Interior Minister Hans-Peter Friedrich criticised US intelligence policy since the first revelations from leaked National Security Agency (NSA) documents came to light.
"The silence leads to there being all sorts of conspiracy theories," he lamented.
Calls were again heard for Germany to grant asylum to Edward Snowden, the former NSA contractor who is behind the leaks that have fed near-daily media reports for months and is wanted in the US on criminal charges.
Friedrich has said the government is studying the possibility of questioning Snowden in Russia where he has temporary asylum, while Berlin has already rejected an asylum bid from him.
The government, accused of having played down the espionage claims before September elections and until Merkel herself became a target, faced criticism from opposition Green and Linke MPs for having failed to stand up to the US.
"One doesn't forge a friendship by ducking the issue and running scared," the Linke's parliamentary group leader Gregor Gysi said, also calling for Snowden to receive the Nobel Peace Prize.
"Germany is only sovereign if it listens to Mr Snowden, protects, grants him asylum and organises his safe residence," he said.
