Sat Mar 29, 2014 5:18PM GMT
German magazine Der Spiegel reported on Saturday that German Chancellor Angela Merkel and former Ukrainian prime minister Yulia Tymoshenko were among the names.
The document showed that the data were collected in May 2009.
The spy agency kept more than 300 reports on Merkel in a special databank about scores of foreign heads of state.
Other world leaders monitored by the US surveillance agency include the heads of Peru, Somalia, Guatemala, Colombia and Belarus.
Snowden’s documents in recent months revealed details about the US government’s snooping operations.
On Friday, General Keith Alexander stepped down from the leadership of the NSA after nearly nine-year tenure.
Global outrage over the spying activities spiked after an earlier document revealed that the NSA had illegally eavesdropped on the phone conversations of 35 world leaders, including the German leader.
Relations between the United States and Germany soured in the wake of revelations that the NSA had spied on Merkel.
Snowden leaked top secret US government spying programs under which the NSA and the Federal Bureau of Investigation are monitoring millions of American and European phone records and tracking the online communications of all people around the world.