File photo of Angela Merkel.
The U.S. National Security Agency tapped phone calls involving German Chancellor Angela Merkel and her closest advisers for years and spied on the staff of her predecessors, according to WikiLeaks.
A report released by the group suggested NSA spying on Merkel and her staff had gone on far longer and more widely than previously realised. WikiLeaks said the NSA targeted for long-term surveillance 125 phone numbers of top German officials.
The release risks renewing tensions between Germany and the United States a month after they sought to put a row over spying behind them, with U.S. President Barack Obama declaring in Bavaria that the two nations were "inseparable allies".
A German government spokesman said on Thursday Berlin was looking into the latest report and reiterated that such events strained German and American intelligence cooperation.
U.S. officials could not immediately be reached for comment.
Friends and associates of former NSA contractor Edward Snowden have denied he is the source of the latest WikiLeaks revelations, suggesting that they likely came from a different and still unidentified leaker deep inside U.S. intelligence.
His friends have said Snowden avoided giving the large tranches of classified documents he downloaded while working at NSA installations to WikiLeaks founder Julian Assange, even though Assange helped arrange for Snowden's flight to and current exile in Moscow.
However, some U.S. officials familiar with the latest leaks said they were unaware of other leakers and believe that one way or another the material newly published by WikiLeaks did somehow originate with Snowden, even if he did not give it directly to Assange.
WikiLeaks published what it said were three NSA intercepts of Merkel's conversations, and data it said listed telephone numbers for the chancellor, her aides, her office and even her fax machine.
"The names associated with some of the targets indicate that spying on the Chancellery predates Angela Merkel as it includes staff of former Chancellor Gerhard Schroeder (in office 1998-2002), and his predecessor Helmut Kohl," WikiLeaks added in a statement.
The intercepts detailed communications from Merkel in 2009 on the international financial crisis, with the crown prince of the United Arab Emirates in 2009 on Iran, and with advisers in 2011 on the euro zone crisis.
The targeted phone numbers included those for the cellphones of senior officials at the chancellery and included that of Ronald Pofalla, Merkel's former chief of staff, WikiLeaks said.
Spying is a sensitive issue in Germany because of the abuses of the Nazi and Communist eras. The Snowden revelations have caused outrage in Germany when they first surfaced.
The spying row has also been stirred by allegations that Merkel's staff gave the German BND foreign intelligence agency a green light to help the NSA spy on European firms and officials.
© Thomson Reuters 2015