The National Security Agency appears to be collecting the telephone records of millions of American customers of Verizon, one of the nation's largest phone companies, under a top-secret court order issued in April.

The order appears to require Verizon to provide the NSA with daily information on all telephone calls by its customers within the United States and from foreign locations into the United States.

The order, which was signed by a judge from the secret court that oversees domestic surveillance, was first reported on the website of The Guardian newspaper. The website reproduced a copy of the order, which two former U.S. officials told The Washington Post appears to be authentic.