The National Security Agency's controversial and alarming data-gathering program records up to a third of American phone call data, the agency has said. Reports in both The Wall Street Journal and The Washington Post, citing anonymous sources and NSA officials, claim that information about between 20 and 30 percent of domestic landline calls is recorded.

However, the agency is reportedly struggling to keep tabs on Americans' cell phone communiqués, in part because it is not permitted to keep records of location data obtained from mobile devices. The reported 20 to 30 percent is not an amount to scoff at, but is considerably less than 2006, during which time nearly all phone records were collected. 

The news comes after a secret US court approved President Obama's order to limit the extent to which surveillance officials can gather bulk phone data, a move that is necessary but may be too little, too late.

[via New York Times]