BERLIN - German ministers on Sunday called for a swift response from the US to allegations of spying by a suspected double agent, which have raised fears of fresh tensions between the two allies.
"If reports are correct, we are not talking here about small potatoes," Foreign Minister Frank-Walter Steinmeier said in a tweet, following reports of US spying that have sparked anger in Germany after revelations the NSA allegedly tapped Chancellor Angela Merkel's phone.
The US ambassador, who was called to a meeting at the foreign ministry late on Friday, had been told Washington is expected to shed light on the reports "as quickly as possible," he added.
Interior Minister Thomas de Maiziere in pre-released experts from Monday's Bild newspaper called for a "quick and clear" statement by the US on the allegations.
The 31-year-old employee of the German foreign intelligence agency known as the BND arrested last week had been working for the CIA for around two years, local media reported Sunday.
"All signs indicate that he was acting for the Americans," the Frankfurter Allgemeine Sonntagszeitung (FAS) Sunday newspaper quoted an unnamed senior official at Germany's foreign intelligence service as saying.
The weekly Bild am Sonntag newspaper, citing information from security authorities, also said the man had worked for the CIA and handed over secret documents as recently as July 1.
Germany's federal prosecutor general confirmed a man was arrested last Wednesday on suspicion of acting for a foreign intelligence service, but did not specify which one.
Both newspapers said the suspect had passed on two documents about a parliamentary panel established earlier this year to investigate NSA surveillance after revelations by fugitive former intelligence contractor Edward Snowden.
German authorities were alerted to the suspect when he sent an email with attached files at the end of May to the Russian consulate offering to supply information, reports said.
President Joachim Gauck said in excepts from an ZDF public TV also released early that, should the suspicions about the US be confirmed, "then it probably really has to be said, now it's enough".
Bild am Sonntag reported the suspect had confessed to handing more than 200 documents to the Americans over the course of two years for which he was paid 25,000 euros ($34,000), during questioning by authorities.
Germans were outraged by revelations last year that the NSA had allegedly eavesdropped on Merkel's conversations, as well as wider US surveillance of Internet and phone communications.
The revelations strained ties between Washington and Germany, a key European ally, which both countries' leaders have been at pains to repair.