WASHINGTON - US legal and intelligence experts ordered by President Barack Obama to review National Security Agency practices on Wednesday called for a sweeping overhaul of US surveillance programs while preserving "robust" intelligence capabilities.
The five-member panel of advisers also urged reforms at a secret national security court and an end to bulk retention of telephone "metadata" by the spy agency, by keeping those records in private hands subject to specific queries from the NSA or law enforcement.
The 308-report also called for "significant steps" to be taken "to protect the privacy of non-US persons," and urged more cooperation with allies to avoid the diplomatic fallout from revelations of US intelligence gathering.
Obama commissioned the review panel report earlier this year in the wake of explosive revelations by fugitive intelligence contractor Edward Snowden on the stunning scope of the NSA's operations.
"It is now time to step back and take stock," the panel said in its report, which was submitted last week to the White House and released publicly Wednesday.
"We conclude that some of the authorities that were expanded or created in the aftermath of September 11 unduly sacrifice fundamental interests in individual liberty, personal privacy, and democratic governance," it said.
The panel said it hoped its recommendations would "strike a better balance between the competing interests in providing for the common defense and securing 'the Blessings of Liberty to ourselves and our Posterity'."
The review board steered away from calling for outright curbs on intelligence on foreign leaders, but said any such surveillance must be based on real security threats and be approved at the highest levels.
"This process should identify both the uses and the limits of surveillance on foreign leaders and in foreign nations," the report said.
Richard Clarke, a former White House counterterrorism aide who is a member of the review board, said, "We are not saying the struggle against terrorism is over."
But Clarke, who joined other review board members at a briefing, added there were "mechanisms that can be more transparent, can have more independent oversight" and cited the need to "give the public a sense of trust that goes beyond what it is today."
Panel members said the recommendations would not necessarily mean a rolling back of intelligence gathering, but that surveillance must be guided by standards and by high-level policymakers.
"In a free society, public officials should never engage in surveillance in order to punish their political enemies; to restrict freedom of speech or religion; to suppress legitimate criticism and dissent; to help their preferred companies or industries; to provide domestic companies with an unfair competitive advantage; or to benefit or burden members of groups defined in terms of religion, ethnicity, race, and gender," the report said.
One of the key recommendations is to reform the law allowing the NSA to hold phone records or "metadata" on millions of calls both within and outside the United States.
"In our view, the current storage by the government of bulk metadata creates potential risks to public trust, personal privacy, and civil liberty," the report said.
The panel suggested that metadata be held by private providers or another private third party, with the government allowed access if "justified".
The report called for limits on "national security letters" that can be issued by the Federal Bureau of Investigation without court oversight to require firms to hand over information.
It also said the secret court handling foreign intelligence requests should have a "public interest advocate" so that it can hear more than only the government's arguments.
And the panel agreed with major technology companies which have been seeking to release more information on the numbers of national security requests they receive, and said the government should release numbers of its own.
The White House said the president "will work with his national security team to study the review group's report, and to determine which recommendations we should implement."
Obama is to give a speech to the American people in January to explain his reasoning, the White House said.
The president has already signaled through senior aides that he will not agree to appoint a civilian head of the NSA. He plans to stick to the tradition by which a uniformed military officer -- who also runs the US military's cyber warfare command -- will run the eavesdropping agency.
The release of the report comes amid deepening political pressure on the White House for significant reforms in the massive NSA telephone and Internet data mining operations in the United States and across the world.
Snowden's revelations -- which have White House officials scrambling to keep up -- have, according to intelligence chiefs, inflicted significant damage on US clandestine operations against terror groups, while deeply embarrassing the Obama administration.
A federal judge in Washington this week ruled that NSA programs, which have scooped up millions of details on telephone calls and Internet traffic on Americans and foreigners, were probably unconstitutional.
The ruling opened a long legal battle which is likely to end up in the Supreme Court.