By Tabassum Zakaria and Deborah Charles
WASHINGTON, Oct 29 (Reuters) - Top U.S. intelligence officials appeared at a congressional hearing on Tuesday amid a public uproar that has expanded from anger over the National Security Agency collecting the phone and email records of Americans to spying on European allies.
But the Republican chairman of the House of Representatives Intelligence Committee, Mike Rogers, warned that collecting foreign intelligence was important to protecting Americans and allies from terrorism.
"Every nation collects foreign intelligence. That is not unique to the United States," he said in opening remarks at the committee's hearing. "What is unique to the United States is our level of oversight, our commitment to privacy protections, and our checks and balances on intelligence collection."
At the hearing, lawmakers will have a chance to question NSA Director General Keith Alexander, NSA Deputy Director Chris Inglis, Director of National Intelligence James Clapper and Deputy Attorney General James Cole.
They are appearing against a backdrop of angry European allies accusing the United States of spying on their leaders and citizens.
The most prominent target appears to have been German Chancellor Angela Merkel, whose government said last week it had learned the United States may have monitored her mobile phone.
More than any previous disclosures from material given to journalists by former NSA contractor Edward Snowden, the reports of spying on close U.S. allies have forced the White House to promise reforms and even acknowledge that America's electronic surveillance may have gone too far.
"We recognize there need to be additional constraints on how we gather and use intelligence," White House spokesman Jay Carney said on Monday.
Congress' top Republican, House Speaker John Boehner, told reporters there should be a review of NSA spying on allied leaders. He said the United States must balance its obligations to allies with its responsibility to keep Americans safe.
Two lawmakers from different political parties introduced legislation to end the government's "dragnet collection" of information. The bill also calls for greater oversight, transparency and accountability for domestic surveillance.
Democratic U.S. Senator Patrick Leahy and Republican Representative James Sensenbrenner, the primary authors of the USA Patriot Act implemented after Sept. 11, 2001, attacks to improve the government's ability to protect its citizens, now want to make sure information gathering does not go too far.
"No one underestimates the threat this country continues to face, and we can all agree that the intelligence community should be given necessary and appropriate tools to help keep us safe," said Leahy, chairman of the Senate Judiciary Committee. "But we should also agree that there must be reasonable limits on the surveillance powers we give to the government."
U.S. Senator Dianne Feinstein, chairwoman of the Senate's intelligence committee, joined the ranks of critics on Monday, expressing outrage at American intelligence collection on allies, and pique that her committee was not informed.
"With respect to NSA collection of intelligence on leaders of U.S. allies - including France, Spain, Mexico and Germany -let me state unequivocally: I am totally opposed," said Feinstein, who has been a staunch defender of some of the NSA programs leaked by Snowden.
The White House is conducting a review of intelligence programs prompted by disclosures about top secret spying programs to the media by Snowden, who is living in Russia, out of reach of U.S. attempts to arrest him.
The testimony of the spy chiefs will cover NSA programs and potential changes to the Foreign Intelligence Surveillance Act, which regulates electronic eavesdropping.
The Senate Intelligence Committee conducted a similar hearing in September at which Feinstein said proposals included putting limits on the NSA's phone metadata program, prohibiting collection of the content of phone calls, and legally requiring that intelligence analysts have a "reasonable articulable suspicion" that a phone number was associated with terrorism in order to query the database.
Rogers said some of the proposals being considered in Congress "would effectively gut the operational usefulness of programs that are necessary to protect America's national security."
And he warned, "We cannot go back to a pre-9/11 mindset and risk failing to 'connect the dots' again."
The allegations of U.S. spying on Merkel and other leaders are likely to have a lasting impact on relations, said Heather Conley, director of the Europe Program at the Center for Strategic and International Studies.
In the last several years, Europeans have been disappointed with the Obama administration over its failure to close the U.S. detention center at Guantanamo Bay, Cuba and its use of drone strikes to kill terrorism suspects. The spectacle of the recent federal government shutdown also dented U.S. prestige in Europe.
"It's just raising really big doubts, uncertainties and question marks about not only the president's leadership but whether the United States is a reliable ally," said Conley, a former deputy assistant secretary of state for Europe.