Mr. Nacchio's statement today made a point of saying that the N.S.A. requests occurred "at a time when there was no investigation of Qwest or Mr. Nacchio." Mr. Nacchio, who left Qwest in 2002 amid allegations of fraud at the company, was indicted in December on 42 charges of insider selling.

Prosecutors say Mr. Nacchio did not make investors aware of warnings from his managers that the company's revenue and profit forecasts were too optimistic. They say Mr. Nacchio kept this information to himself yet also sold 2.5 million shares of Qwest stock over five months in 2001 that netted $100 million. The case could go to trial later this year.On Thursday, some Republicans, including Representative Peter Hoekstra of Michigan, chairman of the House Intelligence Committee, defended the N.S.A.'s activities and denounced the disclosure. Mr. Hoekstra said the report "threatens to undermine our nation's safety."

"Rather than allow our intelligence professionals to maintain a laser focus on the terrorists, we are once again mired in a debate about what our intelligence community may or may not be doing," he said.

But many Democrats and civil liberties advocates said they were disturbed by the report, invoking images of Big Brother and announcing legislation aimed at reining in the N.S.A.'s domestic operations. Fifty-two members of Congress asked the president to name a special counsel to investigate the N.S.A.'s domestic surveillance programs.

Senator Arlen Specter, the Pennsylvania Republican who heads the Judiciary Committee, said the reported data-mining activities raised serious constitutional questions. He said he planned to seek the testimony of telephone company executives.

The House majority leader, John A. Boehner of Ohio, said he wanted more information on the program because "I am not sure why it would be necessary to keep and have that kind of information."

Mr. Bush did not directly confirm or deny the existence of the N.S.A. operation but said that "as a general matter, every time sensitive intelligence is leaked it hurts our ability to defeat this enemy."