Washington - Sen. Chris Dodd, D-Conn., said Thursday that he will block a Senate vote on a White House-backed surveillance bill because it would include legal immunity for telecommunications companies that helped intelligence agencies carry out warrantless surveillance of Americans.

Dodd, a presidential candidate, said he will use his senatorial "hold" power to prevent the Foreign Intelligence Surveillance Act legislation from being considered by the full Senate. The move would effectively stall a measure that President Bush and Director of National Intelligence Mike McConnell have said is essential to protect national security.

Allowing lawsuits to go forward, McConnell has said, could impoverish the companies and make them less able to aid intelligence surveillance efforts.

The bill, which would replace a temporary measure that Congress passed in August, was approved by the Senate Intelligence Committee, 13-2, late Thursday.

"The president has no right to secretly eavesdrop on the conversations and activities of law-abiding American citizens," Dodd said. "Anyone who has aided and abetted him in these illegal activities should be held accountable."

The New York Times in December 2005 reported that the administration eavesdropped without warrants on communications between Americans and foreign intelligence targets under authority it believes the Constitution vests in the president. In May 2006, USA TODAY reported the National Security Agency was collecting and analyzing telephone calling patterns of millions of Americans with the help of the companies.

The administration has defended the warrantless surveillance program as lawful but has not confirmed records sharing.

Three large companies — Verizon, Qwest and AT&T — face multiple civil lawsuits related to their handling of phone records. In letters to a House committee this week, the companies say government secrecy strictures prevent them from effectively defending the lawsuits or even saying the program exists.

The Senate bill approved Thursday allows the companies to have the suits dismissed if the U.S. attorney general attests that they helped programs critical to national security. Even companies that did not help intelligence agencies could also have suits dismissed based on the attorney general's certification to a judge.

The Senate bill also includes a provision backed by Democrats that would require the nation's foreign intelligence court for the first time to approve surveillance of overseas terrorism suspects who communicate with persons in the USA.

Telecoms shouldn't get immunity until the administration provides details on what the carriers did to help intelligence agencies, says Caroline Fredrickson of the American Civil Liberties Union.

"We could be talking about not just lawsuits but lawbreaking," she said.

The bill now goes to the Senate Judiciary Committee, where it faces tough prospects. Patrick Leahy, D-Vt., and Arlen Specter, R-Pa., have said they're unlikely to back retroactive immunity until they learn more about the surveillance programs.

The legislation is stalled in the House.