WASHINGTON -- President Barack Obama’s administration on Thursday defended a newly disclosed National Security Agency program that gathers telephone records of tens of millions of Verizon customers, authorized under a secret court order.

In an unusual move, James Clapper, director of national intelligence, responded to a newspaper report about the program by declassifying certain aspects of the law to explain to the public the limitations of the program. He said it could only be used if there is “a reasonable suspicion” of a connection with a foreign terrorist organization.

“The highest priority of the intelligence community is to work within the constraints of law to collect, analyze and understand information related to potential threats to our national security,” he said in a statement late Thursday.

On Capitol Hill, key lawmakers from both parties said they have known about the program for years, while others said they were never informed of the scope of the collection, which appeared to impact Americans not suspected of any wrongdoing.

“It was like, oh God, not one more thing,” Sen. Barbara Mikulski, D-Md., told Attorney General Eric Holder during an unrelated Appropriations Committee meeting. “And not one more thing where we’re trying to protect America, and then it looks like we’re spying on America.”

The program, first reported Wednesday by the Guardian newspaper in London, requires Verizon to provide the NSA, an intelligence agency within the Department of Defense, with daily information on calls by its customers both in the United States and from foreign locations into the United States. The information includes numbers dialed and received and lengths of calls, but not the content of the calls.

A former senior NSA official said the database is more valuable than the content of communications because it allows the NSA to construct “maps” of an individual’s daily movements, social connections, travel habits and other personal information.

“It gets you a map over time. I get to map movements, connections, communities of interest,” said Thomas Drake, who was charged in 2010 with violating the Espionage Act for leaking information on waste, abuse and fraud at the NSA to a journalist. All of the charges were eventually dropped. The NSA also “can easily associate” a number with an identity, he said in an interview.

Rep. Mike Rogers, R-Mich., chairman of the House Intelligence Committee, said the records had stopped a domestic terrorism plot on American soil in the last few years.

Clapper said that the “unauthorized disclosure of a top secret U.S. court document threatens potentially long-lasting and irreversible harm to our ability to identify and respond to the many threats facing our nation.”

Also Thursday, the Washington Post and the Guardian reported that the NSA and the FBI have been secretly accessing the central servers of nine U.S. Internet companies in a highly classified program called PRISM.

Established in 2007 and expanded ever since, the program accesses audio, video, photographs, emails and other data “that enable analysts to track a person’s movements and contacts over time,” the newspaper said.

Clapper said the articles contain numerous inaccuracies, though he did not say what they are, and reiterated that the law does not allow the targeting of any U.S. citizen or of any person located within the United States.