In a broad defense of the program put forward hours later, a senior intelligence official said the eavesdropping was narrowly designed to go after possible terrorist threats in the United States. The official said that, since October 2001, authorization for the program has been renewed more than three dozen times. On each occasion, the lawfulness of the program is certified by the president's legal counsel and the attorney general. It is then personally signed by Mr. Bush.
Administration officials insist they need an aggressive offense to fight terrorists, reports CBS News correspondent Bill Plante.
"Winning on the war terror requires winning the war of information," said Attorney General Alberto Gonzales.
Before the program began, the NSA typically limited its domestic surveillance to foreign embassies and missions and obtained court orders for such investigations. Overseas, 5,000 to 7,000 people suspected of terrorist ties are monitored at one time.
"This is Big Brother run amok," declared Sen. Edward Kennedy, D-Mass. Sen. Russell Feingold, D-Wis., called it a "shocking revelation" that "ought to send a chill down the spine of every senator and every American."
Government officials credited the new program with uncovering several terrorist plots, including one by Iyman Faris, an Ohio trucker who pleaded guilty in 2003 to supporting al Qaeda by planning to destroy the Brooklyn Bridge, the report said.
Some NSA officials were so concerned about the legality of the program that they refused to participate, the Times said. Questions about the legality of the program led the administration to temporarily suspend it last year and impose new restrictions.
Attorney General Gonzales said Mr. Bush is waging an aggressive fight against terrorism, but one that is "consistent with the Constitution."
But he said generally that the government has an intense need for information in the struggle. "Winning the war on terrorism requires winning the war of information We are dealing with a patient, diabolical enemy who wants to harm America," Gonzales said at a news conference at the Justice Department on child prostitution arrests.
Caroline Fredrickson, director of the Washington legislative office of the American Civil Liberties Union, said the group was shocked by the disclosure.
"We're finding out that the president has possibly authorized the breaking of the law so that our government can eavesdrop on American citizens?" Fredrickson told CBS Radio News. "We're still trying to process it, but it's truly amazing."
Earlier this week, the Pentagon said it was reviewing its use of a classified database of information about suspicious people and activity inside the United States after a report by NBC News said the database listed activities of anti-war groups that were not a security threat to Pentagon property or personnel.
The Times said it delayed publication of the report for a year because the White House said it could jeopardize continuing investigations and alert would-be terrorists that they might be under scrutiny. The Times said it omitted information from the story that administration officials argued could be useful to terrorists.