The National Security Agency has been monitoring the conversations of at least 35 world leaders, according to a document provided to The Guardian by whistleblower Edward Snowden—a new revelation that will likely add to the ongoing furor over the U.S. surveillance of other governments.

According to the documents, U.S. officials from a bevy of departments “who mixed with world leaders and politicians” are routinely called upon by the NSA to hand over contacts and phone numbers of those officials.

Included in the “Rolodexes or phone lists” collected by NSA analysts from “customer” departments, such as the White House, State Department and the Pentagon, was the communication info for 35 thus far unnamed world leaders, leading to the surveillance of their phone calls, according to the documents.

The revelation comes amongst growing tensions between the U.S. and leaders such as German Chancellor Angela Merkel, Brazilian President Dilma Rousseff and President Enrique Pena Nieto of Mexico, over ongoing NSA stories that have shown the U.S. has continuously and vigorously kept a close eye on the communications of those governments.

The Guardian reports:

“In one recent case,” the document states, “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.”

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