WASHINGTON (Reuters) - In defiance of U.S. President George W. Bush, Democrats on Wednesday voted to bolster civil-liberty safeguards in his anti-terror spying program and refused to shield phone companies from pending lawsuits.

Just hours after Bush warned Democrats they would be rolling back efforts to protect against another September 11-type attack, the House of Representatives Judiciary Committee approved legislation to ensure congressional and secret-court oversight of the surveillance of enemy targets. The vote was 20-14.

The measure would require the administration to obtain one-year "blanket warrants" from the U.S. Foreign Intelligence Surveillance Court to monitor telephone calls or e-mails of suspected terrorists when they involve a U.S. citizen.

It would not require individual warrants to listen in on Americans communicating with terrorists, unless the U.S. citizen is also a specific target of the surveillance. No warrant would be needed to monitor foreign suspects speaking to each other overseas.

"The legislation before us today seeks to once again strike the appropriate balance between needed government authority and our precious rights and liberties," said House Judiciary Committee Chairman John Conyers, a Michigan Democrat.

Pending consideration of the bill by the House Intelligence Committee, which worked on it behind closed doors, Democrats hope to get it before the full House for passage next week. The Senate Intelligence Committee is working on its own measure.

Shortly before the Judiciary Committee vote, Bush appeared at the White House to voice concerns about the bill. It would revise a temporary measure he pushed through Congress in August.

That measure, "The Protect America Act" expanded the power of U.S. authorities to conduct warrantless surveillance and closed what the administration said was a dangerous legal gap in its authority.

Bush warned that the new measure "would take us backward."

"The Protect America Act is a vital tool in stopping the terrorists, and it would be a grave mistake for Congress to weaken this tool," Bush said.

The Judiciary Committee rejected an amendment sought by the White House that would have essentially made permanent the temporary act, set to expire in February.

The amendment would also have shielded telecommunications firms retroactively from lawsuits for participating in Bush's warrantless eavesdropping program secretly begun after the September 11 attacks.

The committee-passed bill would protect the firms from future lawsuits, but not from pending ones.

Critics say the program was illegal.

The White House maintains Bush acted within his authority. But it has refused requests by Congress for information specifying what the telecommunication companies did.

The Electronic Frontier Foundation, a privacy advocacy group, sued telephone company AT&T Inc last year and accused it of illegally allowing the government to monitor phone calls and e-mails.

Bush said the new bill "must grant liability protection to companies who are facing multibillion dollar lawsuits only because they are believed to have assisted in the efforts to defend our nation following the 9/11 attacks."

But Rep. Jerrold Nadler, a New York Democrat, said, "Let the courts decide whether these companies ... were acting patriotically with nobility and legally, or if they were breaking the law."

Leading Democrats say they will refuse to consider any retroactive immunity unless the White House provides the requested documents on the spying program.

Rep. Lamar Smith of Texas, top Republican on the Judiciary Committee, ridiculed the bill, formally named The Responsible Electronic Surveillance that is Overseen, Reviewed and Effective Act.

"The Democrat leadership calls the RESTORE Act of 2007 a compromise," Smith said. "I could not agree more. The RESTORE Act of 2007 compromises our national security."