Data 'foiled plots in 20 nations'
Information gleaned from two controversial data-collection programmes run by the National Security Agency thwarted potential terrorist plots in the US and more than 20 other countries, US intelligence officials said.
They also revealed that the gathered data is destroyed every five years.
Last year, fewer than 300 phone numbers were checked against the database of millions of US phone records gathered daily by the NSA in one of the programmes, the intelligence officials said, arguing that the programmes are far less sweeping than their critics allege.
No other new details about the plots or the countries involved were part of the newly declassified information released to Congress on Saturday and made public by the Senate Intelligence Committee.
Intelligence officials said they are working to declassify the dozens of plots NSA chief General Keith Alexander said were disrupted, to show Americans the value of the schemes. But they want to make sure they do not inadvertently reveal parts of the US counter-terrorism strategy in the process.
The release of information follows a bruising week for US intelligence officials who testified in Congress, defending programmes that were unknown to the public - and some politicians - until they were revealed by a series of stories in The Guardian and The Washington Post newspapers.
The details were leaked by former NSA contractor Edward Snowden, who remains in hiding in Hong Kong.
The disclosures have sparked debate and legal action against the Obama administration by privacy activists who say the data collection goes far beyond what was intended when expanded counter-terrorism measures were authorised by Congress after the terror attacks of September 11, 2001.
Intelligence officials said that both NSA programmes are reviewed every 90 days by the secret court authorised by the Foreign Intelligence Surveillance Act.
Records, showing details such as time and length of call, can only be examined for suspected connections to terrorism, they said.