The NSA stored more than 300 secret reports on German Chancellor Angela Merkel, one of the White House's most important allies, in a database that also contained information about scores of other foreign heads of state, according to a Saturday report from Der Spiegel.

The prominent German news magazine said this is just the latest revelation to emerge from the massive collection of sensitive and damaging documents released by Edward Snowden, the former NSA contractor-turned-whistleblower who began leaking top-secret information about United States intelligence-gathering operations last June.

The database of foreign leaders included more than 100 people, according to Der Spiegel, who were listed alphabetically according to first name. In addition to Merkel, heads of state from Peru, Malaysia, Guatemala, Colombia, Belarus and Somalia appeared on the list. Der Spiegel did not specify what types of information the more than 300 reports on Merkel contained.

A separate Der Spiegel report from Saturday said the NSA and its British equivalent also targeted private German companies for clandestine intelligence-gathering operations. German authorities are reportedly considering whether or not to open their own formal espionage investigation into the NSA's activities.

Saturday's news is the latest Snowden leak to strain the relationship between the U.S. and Germany. Last October, it was revealed that the U.S. likely spied on Merkel's personal phone, according to multiple reports. That led to a conversation between Merkel and President Barack Obama in which the German chancellor reportedly warned Obama that, if true, such actions by the U.S. would be "completely unacceptable" and a "grave breach of trust."

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