"If the Americans intercepted cell phones in Germany, they broke German law on German soil," Germany’s Interior Minister Hans-Peter Friedrich told the German newspaper Bild am Sonntag on Sunday, adding, "The confidence in our ally, (the) USA, is shaken."
Friedrich also stated, "Those responsible must be held accountable" and demanded “complete information on all accusations."
The German weekly Der Spiegel said in a report published on Saturday that the magazine had seen secret documents from the NSA which show that Merkel's mobile phone had been listed by the agency’s Special Collection Service (SCS) since 2002.
The report adds that the German chancellor’s mobile number was still on a surveillance list in June 2013.
On Friday, the German government said its intelligence chiefs would visit Washington soon to probe the spying controversy.
Government spokesperson Georg Streiter said that the heads of Germany's foreign and domestic intelligence would hold meetings with the officials from the White House and the NSA.
The Guardian reported on Thursday that the NSA had monitored the telephone conversations of 35 world leaders.
"A US official provided NSA with 200 phone numbers to 35 world leaders … Despite the fact that the majority is probably available via open source, the PCs [intelligence production centers] have noted 43 previously unknown phone numbers. These numbers plus several others have been tasked," according to a classified document provided by US whistleblower Edward Snowden.
"These numbers have provided lead information to other numbers that have subsequently been tasked," it added.
Snowden, a former CIA employee, leaked two top secret US government spying programs under which the NSA and the Federal Bureau of Investigation (FBI) are eavesdropping on millions of American and European phone records and the Internet data from major Internet companies such as Facebook, Yahoo, Google, Apple, and Microsoft.
The NSA scandal took even broader dimensions when Snowden revealed information about its espionage activities targeting friendly countries.
SHI/SHI