US mobile carriers provided some one million records to law enforcement in 2012 related to warrants, wiretaps, location data and "cell-tower dumps," documents released by a US senator showed.
The documents do not detail information handed over to the National Security Agency, which is classified, but the American Civil Liberties Union (ACLU) said the figures nonetheless highlight concerns over privacy laws for mobile phones.
The documents released by Senator Edward Markey showed AT&T and T-Mobile each provided data in 297,000 instances and Verizon in more than 270,000.
Sprint said it had no aggregate count but that it provided real-time location data to law enforcement in 67,000 instances in 2012; it also provided emergency or public safety information in 53,000 cases, 22,000 "pen register trap and trace" requests and 17,400 wiretaps.
Smaller companies also provided data -- Cricket/Leap Wireless in 59,000 instances and US Cellular in 20,000.
Christopher Calabrese, of the ACLU, said the lack of privacy protections for cell data raised concerns.
"Have no doubt, police see our mobile devices as the go-to source for information, likely in part because of the lack of privacy protections afforded by the law," said Calabrese in a statement.
"Our mobile devices quite literally store our most intimate thoughts as well as the details of our personal lives. The idea that police can obtain such a rich treasure trove of data about any one of us without appropriate judicial oversight should send shivers down our spines."
Among the requests are so-called cell-tower "dumps," to records from cell towers of all the phones connected, to allow law enforcement agencies to locate a subject.
AT&T said it received 600 such requests in 2012. Verizon said around eight percent of its 30,000 cell-tower searches were "dumps," or around 2,400.
The companies charge fees in many cases for these services.
AT&T said it collected $10 million in 2012, and that it employs around 100 people full time to handle law enforcement requests.
T-Mobile said it was paid $11 million while Verizon said it received less than $5 million "complying with the many court orders or warrants we receive for wiretaps, pen registers, traps and traces and text message content."
The data comes amid heightened concerns on privacy following revelations that the NSA is scooping up vast amounts of data from the Internet and mobile phones in the United States and around the world.
Calabrese said the cell data underscores a need for reform "that updates our outdated privacy laws by requiring law enforcement to get a probable cause warrant before service providers disclose the contents of our electronic communications to the government. Anything less is unnecessarily invasive and un-American.”