The largest US spy agency has acknowledged that it intercepted private communications of some 35 world leaders.

Officials say an internal review revealed the existence of the international spying operation in the National Security Agency, the Wall Street Journal reports.

It is the first public acknowledgment of intercepting telephone communication of world leaders by the US government.

European politicians have expressed outrage over revelations of US surveillance of German Chancellor Angela Merkel’s phone and mining of data in France.

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