Guardian News and Media/New York

The allegations, reported in the Wall Street Journal late on Thursday, suggest that the US Marshals Service has for seven years flown Cessna aircraft outfitted with “dirtbox” devices that mimic cellular towers, permitting the collection of thousands of unique IDs and location data from users.

According to the Journal the planes operate from at least five metropolitan airports, permitting a “flying range covering most of the US population”.

The reportedly indiscriminate collection would permit the marshals and potentially other justice department agencies to avoid having to seek records from the phone companies themselves, especially in criminal investigations where a court order may be required.

The legal basis for the previously undisclosed programme is unclear. It is not reportedly a national security or counterterrorism programme, but instead used to target crime. The Justice Department is said to have modified the equipment so as not to interfere with 911 emergency calls.

The report comes nearly 18 months after the Guardian published revelations about National Security Agency bulk phone record collection based on leaks by Edward Snowden, prompting widespread Congressional, judicial, political and popular scrutiny of domestic surveillance.

A Justice Department official, speaking on condition of anonymity, would not confirm or deny existence of the programme to collect data using aircraft. But the official insisted the department’s activities were lawful and suggested it had received judicial approval. It is unclear if the congressional committees overseeing the collection of cellphone location and identification data have known about the effort.

“Discussion of sensitive law enforcement equipment and techniques would allow criminal defendants, criminal enterprises or foreign powers to determine our capabilities and limitations in this area. In deploying any such equipment or tactics our federal law enforcement agencies comply with federal law, including by seeking court approval,” the official said.

In official testimony US officials have routinely denied that the NSA collects phone location information in bulk, but they frequently add the caveat “under this programme”, leading to widespread suspicion that other government programs perform that function, and prompting freedom of information requests seeking the truth.

A major surveillance bill, already passed by the House of Representatives, to get the NSA out of the business of much bulk domestic phone records collection is expected to receive a vote in the Senate in the coming days. Numerous court challenges to bulk domestic surveillance are also winding their way through federal courts.

The Federal Bureau of Investigation and intelligence agencies did not immediately respond to questions about the reported cellphone program. The White House declined comment and the Justice Department would not speak on the record.

Michael German, a former FBI agent now with New York University Law School, said: “The government’s attitude seems to be if it can, it should, without regard to the violation of Americans’ rights, so long as nobody knows. The overriding problem is the excessive secrecy that hides the government’s ever-expanding surveillance programs from public accountability.

“This isn’t about tipping off criminals. Every criminal or terrorist I ever worked undercover against knew they were criminals and terrorists, and therefore that there was probable cause to believe they were criminals and terrorists, so the government could get warrants to listen to their calls or search their homes.”

Christopher Soghoian, principle technologist at the American Civil Liberties Union, said: “This is bulk surveillance of a massive amount of people in order to find proverbial needle in a haystack

“Recently the FBI has impersonated members of the Associated Press, Internet repairmen and now it’s impersonating the phone companies. This is just the latest example of them taking impersonation to the extreme.”

He called on Congress to open an investigation into this type of surveillance. Soghoian said telecommunications companies were well aware of the type of technology used in the surveillance “but whether they knew it was being strapped to the bottom of planes is another story”.

Phone companies AT&T and Sprint declined to comment. Telecoms executives speaking on background said that all the major carriers used similar technology and they did not believe the fake towers were part of the cellphone companies’ own networks. Company executives are asking for clarification from the justice department.