Russell Tice, who worked on what are known as "special access programs," has wanted to meet in a closed session with members of Congress and their staff since President Bush announced in December that he had secretly authorized the NSA to eavesdrop on U.S. citizens without a court order. In an interview late Thursday, Tice said the Senate Armed Services Committee finally asked him to meet next week in a secure facility on Capitol Hill.

Tice was fired from the NSA last May. He said he plans to tell the committee staffers the NSA conducted illegal and unconstitutional surveillance of U.S. citizens while he was there with the knowledge of Hayden, who has been nominated to become director of the CIA. Tice said one of his co-workers personally informed Hayden that illegal and unconstitutional activity was occurring.

The Senate Intelligence Committee plans to hold Hayden's confirmation hearing next week. "I think the people I talk to next week are going to be shocked when I tell them what I have to tell them. It's pretty hard to believe," Tice said. "I hope that they'll clean up the abuses and have some oversight into these programs, which doesn't exist right now."

Tice originally asked to meet with the Senate and House Intelligence committees, but they did not respond to his request. The NSA did not reply to written questions seeking comment for this story.

Tice said his information is different from the Terrorist Surveillance Program that Bush acknowledged in December and from news accounts this week that the NSA has been secretly collecting phone call records of millions of Americans.

"It's an angle that you haven't heard about yet," he said.

According to an unclassified resume, Tice was a specialist in space operations systems, command and control warfare, advanced technology and all-source collection analysis. During an 18-year career, he worked on some of the most secretive programs in the government.

Tice would not discuss with a reporter the details of his allegations, saying doing so would compromise classified information and put him at risk of going to jail. He said he "will not confirm or deny" if his allegations involve the illegal use of space systems and satellites.

Tice said he would raise concerns that illegal activity was occurring in electronic reports, but that his comments were deleted from those reports.

Tice was fired last May after the NSA ordered him to undergo psychological evaluations following a separate clash with agency leadership, and psychologists diagnosed him as being paranoid. Tice claimed the order to undergo the evaluations was retaliation for raising concerns. He also said he saw an independent psychologist who found no evidence that he has a mental disorder.

Hayden, on Capitol Hill Friday visiting with lawmakers, defended the secret surveillance programs he oversaw while head of the NSA as lawful and designed to "preserve the security and the liberty of the American people."

Hayden declined to comment on news reports about the NSA's database on private telephone calls, but spoke about the NSA's work in general terms, the Associated Press reported.

"Everything that the agency has done has been lawful. It's been briefed to the appropriate members of Congress," Hayden told reporters. "The only purpose of the agency's activities is to preserve the security and the liberty of the American people. And I think we've done that," he said.

White House Press Secretary Tony Snow said, "We're 100 percent behind Michael Hayden. ... There's no question about that, and [we are] confident that he is going to comport himself well and answer all the questions and concerns that members of the United States Senate may have in the process of confirmation."