"As was indicated, what the intelligence community is doing is looking at phone numbers and durations of calls. They are not looking at people`s names, and they`re not looking at content."
A secret programme called PRISM is the leading source of raw material for the National Security Agency, the secretive US intelligence operation that monitors electronic communications, the Washington Post reported Thursday, citing an internal presentation to senior NSA analysts.
US intelligence services tapped directly into the servers of at least nine leading internet companies including Google, Facebook, Apple, Yahoo, AOL, Skype, YouTube and Microsoft to extract emails, voice calls, videos, photos and other communications from their customers without the need for a warrant.
The PRISM report came a day after British newspaper The Guardian reported on FBI requests for details of all the phone calls that were placed over the network of the leading US telecommunications company Verizon.
"What you`ve got is two programmes that were originally authorized by Congress, have been repeatedly authorized by Congress. Bipartisan majorities have approved," Obama said. "Congress is continually briefed on how these are conducted. There are a whole range of safeguards involved, and federal judges are overseeing the entire programme throughout."
Since taking office in 2009, Obama said he has established an "audit process ... to make sure that we`re - after the fact - making absolutely certain that all the safeguards are being properly observed."
Obama said that the PRISM programme "does not apply to US citizens, and it does not apply to people living in the United States."
European Union Home Affairs Commissioner Cecilia Malmstrom said she was "of course concerned about the possible consequences for EU citizens` privacy, but it`s far too early to draw any conclusions."
She said that EU authorities would be seeking more information from US officials.
Obama said that under the telephone programme, security analysts "sifting through this so-called metadata ... may identify potential leads with respect to folks who might engage in terrorism.
"If the intelligence community then actually wants to listen to a phone call, they`ve got to go back to a federal judge, just like they would in a criminal investigation," Obama said.