Report: US spied on millions of phone calls in Spain — over one month

Report: NSA monitored 60 million phone calls in Spain 0:30

The U.S. National Security Agency spied on tens of millions of phone calls in Spain over a single month last year, according to a Spanish newspaper report published online Sunday evening.

The daily El Mundo ("The World") cited information provided by former U.S. intelligence contractor Edward Snowden that showed that the NSA collected bulk data on 60 million phone calls placed in Spain in December 2012.

The revelation follows a report in the German magazine Der Spiegel ("The Mirror") that the United States may have bugged Angela Merkel's telephone for more than a decade — along with communication devices in some 80 locations around the world, from Paris to Prague.

President Barack Obama reportedly told the German leader he would have halted the hacking if he had known about it, according to Der Spiegel.

The newspaper said Merkel's mobile phone had been listed by the NSA's Special Collection Service (SCS) since 2002 and was still on that list just weeks before Obama visited the capital of Berlin in June.

The agency said it had a "not legally registered spying branch" within the U.S. diplomatic post in Berlin, according to an SCS document cited in the Der Spiegel report. If that branch were exposed, the revelation would cause "grave damage for the relations of the United States to another government," the document said, according to Der Spiegel.

Citing a secret 2010 document, Der Spiegel said branches existed in roughly 80 spots across the globe — including Paris, Madrid, Rome, Prague, Geneva and Frankfurt.

It was not immediately clear whether the SCS had recorded conversations or just collected data, according to Der Spiegel.

Obama reportedly apologized to Merkel when she phoned him Wednesday seeking an explanation, according to Der Spiegel, citing a source in Merkel's office.

Frankfurter Allgemeine Sonntagszeitung, a newspaper, also reported Obama had informed Merkel he was not previously aware of the bugging, according to Reuters.

Obama has ordered a review of U.S. surveillance programs following the leak of documents by Snowden that made waves in the U.S. and around the world.

In a statement released Sunday evening, U.S. National Security Council spokeswoman Caitlin Hayden said an ongoing White House review takes a close look at “the way that we gather intelligence to ensure that we properly account for the security concerns of our citizens and allies and the privacy concerns that all people share, and to ensure that our intelligence resources most effectively support our foreign policy and national security objectives.”

NBC News’ Peter Alexander contributed to this report.