WASHINGTON — Leaked documents showing the National Security Agency overstepped its legal authority thousands of times since 2011 have spurred new calls to restrict surveillance on Americans and threatened to further erode trust in the powerful spy agency.

In an attempt to contain the damage Friday, intelligence officials rushed to brief congressional staffers and the White House issued a statement of support for the NSA, which critics say has violated Americans’ privacy and civil liberties in its efforts to track terrorists and foreign agents.


The latest disclosure by fugitive NSA contractor Edward J. Snowden included an internal report, dated May 2012, that cited 2,776 violations over the previous year of rules meant to protect Americans’ privacy. Most of the abuses involved unauthorized eavesdropping of foreigners in the United States, but more than 800 involved inadvertent collection of telephone or Internet data on Americans.

The classified materials, which were first reported by the Washington Post, make clear that the NSA did not seek to circumvent the law, and most of the abuses appear largely technical or inadvertent in nature. But one document instructed NSA analysts to carefully limit the information they provided to the Foreign Intelligence Surveillance Court, which meets in secret to review and authorize NSA requests.


The leaks came a week after President Obama vowed to restore public confidence in the NSA following months of damaging disclosures. He called on Congress to change part of the Patriot Act to provide additional safeguards over domestic intelligence operations, and he proposed creating a public advocate to challenge the government inside the secret surveillance court.

A White House spokesman, Josh Earnest, sought to allay fears that the NSA is conducting widespread unauthorized surveillance. He said Friday that the documents show the NSA is detecting and reporting potential problems, as required by law.


“This administration is committed to ensuring that privacy protections are carefully adhered to, and to continually reviewing ways to effectively enhance privacy procedures,” Earnest said in a statement from Martha’s Vineyard, where Obama is on vacation with his family.

Of the 2,776 violations cited, 1,904 involved cases in which a foreigner whose cellphone or email was under surveillance entered the United States, where court warrants are required for most eavesdropping. The NSA does not need a warrant to spy overseas.


But the NSA also collected emails and other communications of Americans without authorization, according to the documents.

In one case, the NSA improperly collected and commingled American and foreign emails moving through fiber-optic cables. In October 2011, months after the program had begun, the surveillance court declared it unconstitutional and ordered it shut down.


In 2008, according to the documents, a programming error confused 20, the telephone country code for Egypt, with 202, the area code for Washington, D.C. As a result, calling logs were improperly collected on a “large number” of calls.

Another document instructed NSA analysts to exclude certain information in requests to the surveillance court.


“While we do want to provide our F.A.A. overseers with the information they need, we DO NOT want to give them any extraneous information,” the document said.

The F.A.A. is a reference to a law passed in 2008 that granted new authorities to the NSA in exchange for regular audits from the Justice Department and the Office of the Director of National Intelligence, and periodic reports to Congress and the surveillance court.


NSA officials held a rare on-the-record conference call with reporters Friday to defend the agency’s record and its adherence to the law.

“No one at NSA thinks mistakes are OK,” said John DeLong, the NSA’s director of compliance. “There’s no willful violation here. The fact that this document exists is actually evidence that we take each mistake very seriously.”


In a separate classified briefing for House and Senate staffers, NSA officials said the mistakes reflected a tiny fraction of the 20 million emails, phone conversations and other communications that the agency searches each month, according to congressional officials who were not authorized to be quoted.

Sen. Dianne Feinstein (D-Calif.), who chairs the Senate Intelligence Committee, rose to the NSA’s defense. Congress has been regularly informed about compliance problems, most of which “do not involve any inappropriate surveillance of Americans,” she said.


But the Senate oversight committee “can and should do more to independently verify that NSA’s operations are appropriate, and its reports of compliance incidents are accurate,” she added.

Rep. Mike Rogers (R-Mich.), who chairs the House intelligence committee, vowed to reduce the errors. “Human and technical errors … are unfortunately inevitable in any organization and especially in a highly technical and complicated system like NSA,” he said.


Other lawmakers offered sharper criticism.

Rep. C.A. Dutch Ruppersberger (D-Md.), ranking member on the House intelligence committee, called the violations of private rules “incredibly troubling.”


“If accurate, this is outrageous, inappropriate and must be addressed,” said Rep. Mike Thompson (D-St. Helena), who also serves on the intelligence committee.

“I remain concerned that we are still not getting straightforward answers from the NSA,” said Sen. Patrick J. Leahy (D-Vt.), who chairs the Judiciary Committee.


Sens. Ron Wyden (D-Ore.) and Mark Udall (D-Colo.), members of the Senate intelligence committee who have been critical of the NSA, called on the White House to release more information.

“The American people have a right to know more details about the scope and severity of these violations,” they said in a joint statement that called the violations “just the tip of a larger iceberg.”


ken.dilanian@latimes.com