US infiltrated into Google,Yahoo centres

By tapping those links,the agency has positioned itself to collect at will from hundreds of millions of user accounts,many of them belonging to Americans,

The Washington Post said in an exclusive report,adding that the NSA does not keep everything it collects,but it keeps a lot.

The report,however,has been denied by NSA,whose chief General Keith Alexander said that such an activity to his knowledge has never happened. Both Google and Yahoo expressed concern over this.