Chancellor Angela Merkel has expressed concern about reports that a German intelligence officer worked as a double agent for the United States. Bilateral ties had already been strained by reports of snooping by the NSA.
Speaking to reporters during a visit to Beijing on Monday, the chancellor said that if the reports that an employee of Germany's BND intelligence service passed information on to a US contact proved to be true, it would be a "serious case."
Merkel added that she would regard this as "a clear contradiction as to what I regard as trusting cooperation between agencies and partners."
According to the DPA news agency, the employee in question, a 31-year-old man who was arrested last Wednesday, has admitted to passing on more than 200 documents to US intelligence agencies in return for a total of 25,000 euros ($34,000) over a period of two years.
The BND has said the documents that were passed on contained no sensitive information.
Case under investigation
Foreign Minister Frank-Walter Steinmeier, meanwhile, rejected opposition calls for Berlin to expel the US ambassador to Germany. Steinmeier told reporters at a press conference in the Mongolian capital, Ulan Bator, than no further action would be taken until the results of an investigation into the matter were known.
On Friday, the German foreign office called in the US ambassador to express Berlin's displeasure.
Whatever the ambassador told foreign office officials does not appear to have satisfied them, as the controversy showed no sign of dying down by Monday morning.
"I expect now for everyone to assist in the speedy clarification of the accusations, and quick and clear statements, also by the US," Interior Minister Thomas de Maiziere said in comments published in Monday's edition of the mass-circulation Bild newspaper.
On Sunday, even German President Joachim Gauck, whose role is largely ceremonial, weighed in on the issue.
"If it really is the case that a service has been using an employee from our service in this way, we have to say: 'That is enough'," the former Protestant pastor and human rights campaigner in the former communist East Germany said.
There has still been no official comment on the issue from the United States.
"We continue to decline comment," Caitlin Hayden, spokesman for the US National Security Council said on Sunday.
The allegations against the BND employee come with bilateral relations between Germany and the US still strained over revelations by former US National Security Agency (NSA) contractor Edward Snowden.
Among the allegations were that the NSA not only conducted mass surveillance on German citizens, but also hacked into Chancellor Merkel's cellular phone.
pfd/tj (dpa, Reuters)