The U.S. government gained sweeping access to international banking records as part of a secret program to choke off financial support for terrorism, officials confirmed Thursday.

Treasury Department officials said they used broad subpoenas to collect the financial records from an international system known as Swift. Stuart Levey, Treasury's undersecretary for terrorism and financial intelligence, called the subpoenas "a legal and proper use of our authorities."

"Since immediately following 9-11, the American government has taken every legal measure to prevent another attack on our country," Dana Perino, deputy White House press secretary, said Thursday evening. "One of the most important tools in the fight against terror is our ability to choke off funds for the terrorists."

The White House and Treasury Department issued statements about the secret subpoenas after The New York Times, The Wall Street Journal and the Los Angeles Times posted stories about the program on their Web sites.

Under the program, which started shortly after the Sept. 11, 2001 attacks, U.S. counterterrorism analysts combed Swift's massive data base looking for financial transactions by suspected terrorists, according to the newspapers' accounts. They said the program was run by the CIA and overseen by the Treasury Department.

Swift, or the Society for Worldwide Interbank Financial Telecommunication, is a Belgium-based cooperative that handles financial message traffic from 7,800 financial institutions in more than 200 countries.

The administration defended use of the program, saying it plays a vital role in their efforts to identify terrorist financiers.

"Our subpoena of terrorist-related records from Swift has provided us with a unique and powerful window into the operations of terrorist networks," Levey said.

Both he and Perino expressed concern that public disclosure of the program could undermine their terror-tracking efforts.

"We know the terrorists pay attention to our strategy to fight them, and now have another piece of the puzzle of how we are fighting them," Perino said. "We also know they adapt their methods, which increases the challenge to our intelligence and law enforcement officials."

Perino added: "The president is concerned that once again The New York Times has chosen to expose a classified program that is working to protect our citizens."

The Times said administration officials had requested that the newspaper not publish the article.

Bill Keller, the Times' executive editor, said it considered the administration's arguments but in the end decided to publish. "We remain convinced that the administration's extraordinary access to this vast repository of international financial data, however carefully targeted use it may be, is a matter of public interest."

The CIA declined to comment. Since 9/11, the agency has worked closely with Treasury to track terrorists.

Some in Congress were briefed on the operations, including members of the House Intelligence Committee. Chairman Peter Hoekstra, R-Mich., declined to comment.