The Obama administration on Thursday defended its collection of a massive amount of telephone records from at least one carrier as part of U.S. counterterrorism efforts, re-igniting a debate over privacy even as it called the practice "critical" to protecting Americans from attacks, Reuters reports. The admission came after Britain's Guardian newspaper published on Wednesday a secret court order related to the records of millions of Verizon Communications customers. A senior White House official said the metadata request included phone numbers and length of calls but not users' personal information or the calls' content. Such information is "a critical tool in protecting the nation from terrorist threats to the United States," the official said, speaking on the condition of anonymity. "It allows counter-terrorism personnel to discover whether known or suspected terrorists have been in contact with other persons who may be engaged in terrorist activities, particularly people located inside the United States." But privacy and free speech advocates say the president has overstepped his bounds, again. His administration is already under fire for searching Associated Press journalists' calling records and the emails of a Fox News Channel reporter as part of its inquiries into leaked government information. Verizon has declined to comment. It remains unclear whether the practice extends to other carriers, though several security experts and at least one U.S. lawmaker said that was likely.