Use of cellphone 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. And 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 the 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.

Stingrays can be deployed from both the ground and air and work by mimicking cellular base stations to secretly spy on a target mobile phone. Although they can be useful in law enforcement, privacy advocates have argued that the technology can easily be abused to harvest data from vast swaths of non-criminal suspects, possibly violating the U.S. Constitution.

Monday’s committee report offered a glimpse into the scale of the U.S. government’s Stingray use, which has often been shrouded in secrecy. For instance, the Justice Department has 310 devices, and spent $71 million from 2010-2014 on the technology.

Meanwhile, the Department of Homeland Security has 124 devices, and spent $24 million on the tech during the same period. DHS also gave $1.8 million to state and local police to buy Stingrays through grant money.

Cost of an individual Stingray can range from $41,500 to as much as $500,000, according to the committee’s report.

In 2015, both Justice Department and DHS issued new policies on the technology, requiring that a search warrant be obtained before a Stingray can be used. But 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 Department of Justice has learned of “isolated incidents” where private entities may have used Stingrays, a possible violation of U.S. law, the report said.

“One can imagine scenarios where criminals or foreign agents use this type of technology to intercept text messages and voice calls of law enforcement, corporate CEOs, or elected officials,” the report warned.

Although the technology is a valuable law enforcement tool, the bipartisan committee nevertheless wants to limit its use and has put forth a list of recommendations. This includes the U.S. government passing legislation on a nationwide framework on how geolocation information can be access and used.

It’s also asking that state and local police follow the policies the Justice Department and DHS are using in regards to Stingray use. Law enforcement should also be candid with courts regarding the technology's deployment during criminal investigations, the committee's report said.