Use of cell-phone spying technology has become widespread among U.S. law enforcement agencies and should be better regulated, according to a new congressional report.

Not only is the FBI deploying the technology, commonly called "Stingray" after one product made by Harris Corp., but so are state and local police. There are concerns that some law enforcement agencies have used Stingrays without securing search warrants, said the report from House Committee on Oversight and Reform, published on Monday.

"Absent proper oversight and safeguards, the domestic use of (Stingrays) may well infringe upon the constitutional rights of citizens to be free from unreasonable searches and seizures," it said.

The report focuses on privacy concerns with the controversial surveillance device, which can intercept a phone's location, along with calls, SMS text messages, and websites visited on the device.

[...] In 2015, both the Justice Department and the DHS issued new policies on the technology, requiring that a search warrant be obtained before a Stingray can be used. Prior to that, the two departments relied on varying policies that didn't always demand probable cause, the committee's report said.

State and local police are also using the technology without a uniform policy. In addition, the Justice Department has learned of "isolated incidents" where private entities may have used Stingrays, a possible violation of U.S. law, the report said.