The U.S. National Security Agency (NSA) will end its vacuuming of Americans' phone records by Sunday and replace the practice with more tightly targeted surveillance methods, the Obama administration said on Friday. As required by law, the NSA will end its wide-ranging surveillance program by 11:59 p.m. EST Saturday and expects to have the new system in place by then, the White House said.

The transition comes two and a half years after the controversial program was exposed by former NSA contractor Edward Snowden.

Under the Freedom Act, the NSA and law enforcement agencies can no longer collect telephone calling records in bulk in an effort to sniff out suspicious activity.

Instead analysts must now get a court order to ask telecommunications companies to enable monitoring of call records of specific people or groups for up to six months.

Metadata collected by the NSA over the past five years will be preserved for "data integrity purposes" through February 29, the White House said.