Declan McCullagh/CNET

"Follow the Money" is not just a catchphrase but an actual branch within the National Security Agency that spies on payments processed by Visa and others, according to Der Spiegel.

Citing documents from 2010 leaked by former NSA contractor Edward Snowden, the German news magazine reported Monday that the "Follow the Money" division funnels the data it gathers into its own financial database. In 2011, that database held 180 million records, with 84 percent of them credit card transactions.

In response to a request for comment, an NSA spokesperson sent the following statement to CNET:

The U.S. Government acquires information about economic and financial matters to combat a range of threats to the national security of the United States and its allies, including information about terrorist financing and terror networks. This information is collected through regulatory, law enforcement, diplomatic, and intelligence channels, as well as through undertakings with cooperating foreign allies and partners.

The NSA examines the transactions of customers of large credit companies such as Visa as part of its overall surveillance, Der Spiegel said. Specifically, the agency looks for international ties by targeting Visa customers in Europe, the Middle East, and Africa.

In response to the findings, a Visa spokesperson issued the following statement to Der Spiegel:

We are not aware of any unauthorized access to our network. Visa takes data security seriously and, in response to any attempted intrusion, we would pursue all available remedies to the fullest extent of the law. Further, its Visa's policy to only provide transaction information in response to a subpoena or other valid legal process.

Even fellow members of the intelligence community have expressed concerns about the NSA's tracking of financial transactions, Der Spiegel noted. UK intelligence agency GCHQ, which has worked with the NSA, said in a document that the data collection involved "bulk data" full of "rich personal information," much of which "is not about our targets."