The U.S. National Security Agency broke into the Yahoo and Google data centers around the world and gathered information from hundreds of millions of user accounts, The Washington Post reported Wednesday.

The Post cited documents leaked by former NSA contractor Edward Snowden, currently in exile in Russia, as sources for the report.

According to a secret tabulation dated Jan. 9, 2013, the NSA every day sent millions of files from the internal Yahoo and Google networks to its headquarters at Fort Meade, on the outskirts of Washington.

Over the 30-day period ending on that date, the NSA processed more than 181 million new files, including information about the senders and recipients of e-mails and the content of those messages.

The NSA's main tool for undertaking this massive data collection effort is a project called MUSCULAR, which is operated jointly with the agency's British counterpart, GCHQ, The Post said.

From undisclosed interception points, the NSA and GCHQ copy the full scope of data flowing through fiber optic cables transmitting information between the Google and Yahoo global data centers.

White House officials and personnel in the office of National Intelligence Director James Clapper refused to confirm the alleged infiltration of the Google and Yahoo networks by the NSA. EFE