Verizon on Wednesday became the first US telecom carrier to release a "transparency report," and said it received 320,000 data queries last year in the United States. Verizon also said it received between 1,000 and 2,000 "national security letters" from US officials, and had law enforcement requests in 13 other countries where it has operations.

Big technology firms including Google, Apple and Microsoft have been also issuing the transparency reports. AT&T also said last month it would issue a report.

Verizon said its 2013 data for the United States included subpoenas, court orders, warrants and emergency requests from law enforcement.

"We do not release customer information unless authorized by law, such as a valid law enforcement demand or an appropriate request in an emergency involving the danger of death or serious physical injury," the company said in the report.

More than 164,000 of the requests were subpoenas from US law enforcement.

"The subpoenas we receive are generally used by law enforcement to obtain subscriber information or the type of information that appears on a customer’s phone bill," the company said.

"More than half of the subpoenas we receive seek only subscriber information: that is, those subpoenas typically require us to provide the name and address of a customer assigned a given phone number or IP address."

It also received more than 70,000 court orders and 36,000 warrants which require probable cause that the data sought is linked to a crime, Verizon said.

Outside the United States, the largest number of requests came from Germany (2,996) and France (1,347), Verizon said.