WASHINGTON—The Justice Department will start revealing more about the government’s use of secret cellphone tracking devices and has launched a wide-ranging review into how law-enforcement agencies deploy the technology, according to Justice officials.

In recent months, the Federal Bureau of Investigation has begun getting search warrants from judges to use the devices, which hunt criminal suspects by locating their cellphones, the officials said. For years, FBI agents didn’t get warrants to use the tracking devices.

Senior officials have also decided they must be more forthcoming about how and why the devices are used—although there isn’t yet agreement within the Justice Department about how much to reveal or how quickly.

The Justice Department is urging more transparency over the use of secret cellphone tracking devices and reviewing the way they are used in law-enforcement agencies. WSJ’s Devlin Barrett joins MoneyBeat.

The move comes amid growing controversy over the Justice Department’s use of such devices, some versions of which, as The Wall Street Journal reported last year, are deployed in airplanes and scan data from thousands of phones used by Americans who aren’t targets of investigations.

There are still many instances where law enforcement doesn’t get warrants before using the devices, sometimes called “IMSI catchers” and known by various names like Stingray, Hailstorm, and “dirtbox,” according to officials’ public statements. The agencies that use the devices within the Justice Department—the FBI, the U.S. Marshals Service and the Drug Enforcement Administration—each have different rules and procedures for their use.

The Justice Department review will determine how they should be used, officials said.

A Justice spokesman said the department is “examining its policies to ensure they reflect the Department’s continuing commitment to conducting its vital missions while according appropriate respect for privacy and civil liberties.”

The devices were first designed more than a decade ago to hunt terrorists and spies overseas, but they are increasingly in the hands of local police departments that use them to hunt all manner of criminals—from kidnappers to everyday thieves.

The use of the technology, and the tight secrecy that surrounds it, has begun to anger some judges and lawmakers.

Government cellphone-tracking devices can scan data from thousands of phones used by Americans who aren’t targets of investigations. Photo: MIKE BLAKE/REUTERS

Federal law-enforcement and phone-company officials also have expressed concerns that some local police authorities were abusing a legal shortcut by submitting an inordinate number of requests for cellphone information, according to people familiar with the matter. A Baltimore police official, for example, told a local judge overseeing a murder case last month the department had used the devices at least 4,300 times dating to 2007. The judge ruled the use of the device in that case was permissible.

One of the most effective ways to find a suspect using the technology is to get the last known location of the suspect’s phone—which can be provided by a phone company. Some companies can “ping” a phone in real time to determine its general whereabouts while others can tell investigators where it made its last call or text.

The Journal last year detailed how the U.S. Marshals Service flies planes equipped with the devices from airports around five major U.S. cities, scanning tens of thousands of phones at a time in densely populated areas as it hunts for fugitives. The Justice Department also uses them outside U.S. soil, and a Marshals employee was shot last July in a secret operation with such a device in Mexico, leading some law-enforcement officials to question how Justice Department managers decide to deploy them.

The Senate Judiciary Committee has demanded more details from the Justice Department about their use in response to the articles.

“We know it’s got to come out,” one law-enforcement official said. “At some point, it becomes more harmful to try to keep it secret than to acknowledge it. We just want to acknowledge it carefully and slowly, so we don’t lose what is a very effective tool.”

Officials said they don’t want to reveal so much that it gives criminals clues about how to defeat the devices. Law-enforcement officials also don’t want to reveal information that would give new ammunition to defense lawyers in prosecutions where warrants weren’t used, according to officials involved in the discussions.

And one federal agency, the U.S. Marshals, are fugitive-hunters who rarely testify in court, so they are likely to reveal much less about how they use the technology than their counterparts at the FBI and DEA, these people said.

Law-enforcement officials say they aren’t interested in gathering large amounts of information with the devices and say their purpose is typically finding a single suspect in a sea of floating digital data. Privacy advocates say the methods amount to a digital dragnet—a silent ID check of untold numbers of innocent people who aren’t suspected of anything, or even aware their phones are being checked. The machines can also interrupt service on cellphones being scanned.

The effectiveness of the technology in finding suspects is prompting some local law enforcement to use it frequently.

About a year ago, Baltimore police officials began deluging some phone companies with requests for customer cellphone information, claiming it couldn’t wait for a judge’s order, according to people familiar with the matter. Normally, police need a court order to get that kind of information about a phone customer. But there is an exception for emergency requests. Phone companies’ rules vary, but they generally allow emergency requests to be fulfilled in missing-persons cases or when there is a risk of death or serious injury. Typically, the phone company employee doesn’t ask questions to verify the nature of the emergency.

Local police departments must sign a nondisclosure agreement with the FBI before getting access to the technology—agreeing not to reveal details of how the technology works and to seek guidance from the FBI if questioned in court or elsewhere. As part of that agreement, police agencies acknowledge they may have to drop charges against suspects if prosecuting a suspect risks revealing information about the machines.

In contrast, the FBI doesn’t require or provide legal standards to police on best practices for how to use the devices, according to people familiar with the issue. Officials say that if a police department asks for advice on how they use the devices, the FBI will provide it.

People familiar with the Baltimore matter said police there have scaled back their emergency requests.

But some phone company officials remain concerned the emergency request function is prone to abuse, according to people familiar with the issue. A spokesman for the police department didn’t respond to requests for comment.

Verizon Wireless, the nation’s largest cellphone provider, saw an 8% increase in emergency requests by law enforcement nationwide from the first half to the second half of 2014, according to company data.

The overall number of law-enforcement requests fell by 7% from the first half, according to Verizon. AT&T Inc. data showed a 4% increase in emergency law-enforcement requests along with an increase in nonemergency requests. Emergency requests encompass a range of issues, including trying to track information from dropped 911 calls.

In a federal court filing last year in Atlanta, AT&T broadly discussed the increasing demands that law enforcement is putting on phone companies.

“AT&T receives and responds to an enormous volume of official demands to provide information to federal, state, and local law enforcement agencies in the United States,” lawyers for the company wrote in the filing.

The company has more than 100 full-time employees staffed to meet the volume of requests from law enforcement and civil lawsuits.

Write to Devlin Barrett at devlin.barrett@wsj.com