A civil liberties group sued AT&T Inc. on Tuesday for its alleged role in helping the National Security Agency spy on the phone calls and other communications of U.S. citizens without warrants.

The class-action lawsuit, filed in U.S. District Court in San Francisco by the Electronic Frontier Foundation, seeks to stop the surveillance program that started shortly after the 2001 terrorist attacks. It also seeks billions of dollars in damages.

The EFF claims the San Antonio-based telecommunications company not only provided direct access to its network that carries voice and data but also to its massive databases of stored telephone and Internet records that are updated constantly.

"Our main goal is to stop this invasion of privacy, prevent it from occurring again and make sure AT&T and all the other carriers understand there are going to be legal and economic consequences when they fail to follow the law," said Kevin Bankston, an EFF staff attorney.

President Bush has acknowledged authorizing the super-secret NSA to eavesdrop on international phone calls and e-mails of people within U.S. borders without the approval of a court, as required by existing surveillance and wiretapping laws.

The White House has vigorously defended the program, saying the president acted legally under the constitution and a post-Sept. 11 congressional resolution that granted him broad power to fight terrorism.

Democrats and civil libertarians disagree with the program's defenders, and it has already resulted in lawsuits against the federal government and plans for congressional hearings.

In its lawsuit, the EFF claims AT&T violated U.S. law and the privacy of its customers as part of the "massive and illegal program to wiretap and data-mine Americans' communications." The group said it identified AT&T through news reports and its own investigation.

"We are quite confident that discovery would reveal evidence proving our allegations correct," Bankston said.

Michael Balmoris, an AT&T spokesman, said the company does not comment on matters of national security or on pending litigation.

The NSA also did not immediately return a phone message seeking comment.

The EFF lawsuit will not just be fought by AT&T but also the government, which could seek to remove evidence that's sensitive to national security.

"I think we are going to definitely have a fight on state-secret issues," Bankston said. "I would also point out that the state-secret privilege has never come up in a case where the rights of so many have been at issue."

The lawsuit names both AT&T Inc. and its predecessor, AT&T Corp. Last year, SBC Communications Inc. purchased AT&T Corp. and renamed itself AT&T Inc.