US President Barack Obama speaks to the press at Villa Madama in Rome, on March 27, 2014

President Barack Obama put forward a long-awaited plan Thursday to end the US government's bulk collection of telephone records, aiming to defuse a controversy over surveillance on millions of Americans.

Responding to a global outcry over the National Security Agency's extensive eavesdropping programs, Obama's plan would require telephone companies to hold data for the same length of time they currently do, with government agencies allowed to access it with court approval.

The formal announcement represents the president's proposals to reform procedures at the NSA, which was rocked by disclosures about its activities in documents leaked by former intelligence contractor Edward Snowden.

"I have decided that the best path forward is that the government should not collect or hold this data in bulk," Obama said in a White House statement.

Obama said his plan, which needs congressional approval, would tread a line that allows the government to conduct surveillance to thwart terror attacks while also addressing the public's privacy concerns.

But civil liberties groups said the president's proposals on data collection failed to answer key details and they were skeptical if substantive changes would occur.

'Emergency' exceptions

The White House said the NSA would need a court order to access the data, except in "an emergency situation" it did not define.

In those circumstances, the court would be asked to approve requests based on specific telephone numbers "based on national security concerns," it added.

Bays of equipment line the 2G area at an AT&T mobile telephone switching office on October 25, 2012 in Charlotte, North Carolina

"This approach will best ensure that we have the information we need to meet our intelligence needs while enhancing public confidence in the manner in which the information is collected and held," Obama said.

Because the new plan would not be in place by a March 28 expiration date, the president said he would seek a 90-day reauthorization of the existing program from the Foreign Intelligence Surveillance Court, with some modifications he ordered in January.

"I am confident that this approach can provide our intelligence and law enforcement professionals the information they need to keep us safe while addressing the legitimate privacy concerns that have been raised," he said.

A trove of disclosures by Snowden, now a fugitive granted temporary exile in Russia, resulted in widespread condemnation of spying efforts at home and abroad, given the vast capabilities of America's intelligence programs.

Officials have defended the methods as necessary to thwart attacks on US and foreign soil, but the sheer scope of the NSA's domestic activities divided opinion.

"We hope the Congress can act swiftly," a senior US official said in a conference call explaining the plan.

A fact sheet released by the White House said that if the plan were implemented, "absent an emergency situation, the government would obtain the records only pursuant to individual orders from the FISC approving the use of specific numbers for such queries, if a judge agrees based on national security concerns."

Unsatisfied critics

Obama provided an outline for his plan earlier this week, eliciting guarded optimism from privacy and civil liberties activists, but Thursday's announcement left many NSA critics unsatisfied.

Amie Stepanovich at the digital rights group Access said Obama's plan is "a significant step forward," but "fails to address many of the problems with US government surveillance policies and programs, such as the double standard for citizens and those outside of the United States."

Obama's plan "does not go nearly far enough," David Segal of Demand Progress said, calling for measures to protect people's email and Internet communications.

And Alex Abdo at the American Civil Liberties Union said the planned changes could still allow surveillance to "balloon out of control."

"One of the most important details is whether we continue to allow the government to engage in the suspicionless surveillance of innocent Americans," Abdo said in a statement.

A bipartisan group of lawmakers this week proposed a plan similar to the president's, but some activists are pushing for deeper reforms to limit mass surveillance.

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