By Caren Bohan
WASHINGTON (Reuters) - Lawmakers called on Sunday for a review of the government's monitoring of phone and Internet activities, and one Democrat urged a reopening of the Patriot Act, the post-September 11, 2001 law that gave intelligence agencies broader surveillance powers.
President Barack Obama's administration has come under criticism after the disclosure that the super-secret National Security Agency has been collecting massive amounts of data from private companies on phone calls and emails.
As lawmakers debated the implications of the U.S. surveillance programs that were first reported in Britain's Guardian and The Washington Post, the Guardian identified a 29-year-old former CIA technical worker as the source of the leaks about the spy agencies.
The Guardian said its source, Edward Snowden, had asked the newspaper to reveal his identity.
The surveillance activity has stirred a debate over privacy rights in the United States.
Senator Mark Udall, a member of the Intelligence Committee, said he thought another look at the 2001 U.S.A Patriot Act was warranted.
"I think we ought to reopen the Patriot Act and put some limits on the amount of data that the National Security (Agency) is collecting," Udall told the ABC program "This Week."
He said there must be a balance between protecting the country against terrorist attacks and respecting Americans' constitutional rights, including the Fourth Amendment protection against unlawful search and seizure.
"It ought to remain sacred, and there's got to be a balance here. That is what I'm aiming for. Let's have the debate, let's be transparent, let's open this up," he said. "I don't think the American public knows the extent or knew the extent to which they were being surveilled and their data was being collected."
Still, two senior lawmakers said the surveillance programs had helped to prevent attacks on the United States and have been subjected to strict oversight.
"These programs are within the law," said Dianne Feinstein, the Democratic chairwoman of the Senate Intelligence Committee, told "This Week."
"Part of our obligation is keeping Americans safe," added Feinstein. "Human intelligence isn't going to do it."
Republican Mike Rogers, chairman of the House of Representatives Intelligence Committee, agreed with Feinstein that the programs were important for national security.
"One of the things that we're charged with is keeping America safe and keeping our civil liberties and privacy intact. I think we have done both in this particular case," he said.
The mining of phone records from millions of American customers of a subsidiary of Verizon Communications drew the most concern from lawmakers.
A separate, highly classified program, code-named Prism, has given federal authorities access to data from companies including Google Inc., Apple Inc and Facebook Inc on emails, photos and other files, according to the Washington Post.
James Clapper, the director of National Intelligence, acknowledged the existence of the Prism program for the first time in a statement on Saturday and said it is legal and not aimed at U.S. citizens.
Lawmakers who defended the NSA surveillance said it helped to thwart an Islamic militant plot to bomb the New York City subway system in 2009.
Congressman Michael McCaul, the chairman of the House Homeland Security Committee, said protecting American lives was the most important mission. But McCaul, a Texas Republican, said one way to ease some concerns about the phone records program might be to curtail the government's role in storing the data and turn that responsibility over to private companies.
"I think it's the warehousing of all the phone records from all the major carriers within the federal government is what gives most people the great concern," McCaul said. "I think it could be run through the private sector as we used to do it, and that's something I think we'll be looking at in the Congress."
Republican Senator Rand Paul of Kentucky, a potential 2016 presidential candidate, has been one of the most vocal critics of the surveillance. Paul told "Fox News Sunday" he would consider a legal challenge to the constitutionality of the mining of phone records.
"They are looking at a billion phone calls a day from what I read in the press and that doesn't sound to me like a modest invasion of privacy. It sounds like an extraordinary invasion of privacy," Paul said.
Republican Senator John McCain said it made sense for Congress to review the surveillance programs but told CNN he believed they were needed because threats to the United States from abroad have been "growing, not diminishing."
"I do believe that if this was September 12th, 2001, we might not be having the argument that we are having today," the Arizona senator said.
(Additional reporting by Paul Simao and David Morgan; Editing by Doina Chiacu and Cynthia Osterman)