A published report says the National Security Agency has collected millions of contact lists from personal email and instant messaging accounts around the world _ including those of Americans _ in its effort to find links to terrorism or other criminal activity.

The Washington Post said late Monday it learned about the effort from secret documents provided by NSA leaker Edward Snowden and confirmed by senior intelligence officials.

The Post says the spy agency intercepts hundreds of thousands of email address books every day from private accounts on Yahoo, Gmail, Facebook and Hotmail. The NSA also collects about a half-million buddy lists daily from chat services and email accounts.

A government spokesman says the agency gains intelligence on valid targets and has no interest in personal information from ordinary Americans. (AP)