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

She added: "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. We also know they adapt their methods, which increases the challenge to our intelligence and law enforcement officials."

Referring to the disclosure by The New York Times last December of the National Security Agency's eavesdropping program, she said, "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."

Swift declined to discuss details of the program but defended its role in written responses to questions. "Swift has fully complied with all applicable laws," the consortium said. The organization said it insisted that the data be used only for terrorism investigations and had narrowed the scope of the information provided to American officials over time.

A Crucial Gatekeeper

Swift's database provides a rich hunting ground for government investigators. Swift is a crucial gatekeeper, providing electronic instructions on how to transfer money among 7,800 financial institutions worldwide. The cooperative is owned by more than 2,200 organizations, and virtually every major commercial bank, as well as brokerage houses, fund managers and stock exchanges, uses its services. Swift routes more than 11 million transactions each day, most of them across borders.

The cooperative's message traffic allows investigators, for example, to track money from the Saudi bank account of a suspected terrorist to a mosque in New York. Starting with tips from intelligence reports about specific targets, agents search the database in what one official described as a "24-7" operation. Customers' names, bank account numbers and other identifying information can be retrieved, the officials said.

Image Data provided by the program helped identify Uzair Paracha, a Brooklyn man who was convicted on terrorism-related charges in 2005, officials said.

The data does not allow the government to track routine financial activity, like A.T.M. withdrawals, confined to this country, or to see bank balances, Treasury officials said. And the information is not provided in real time — Swift generally turns it over several weeks later. Because of privacy concerns and the potential for abuse, the government sought the data only for terrorism investigations and prohibited its use for tax fraud, drug trafficking or other inquiries, the officials said.