An agency of the U.S. Justice Department is collecting data from thousands of cell phones, both criminal suspects and innocent Americans, by using fake communications towers on airplanes, according to a report by The Wall Street Journal.

The U.S. Marshals Service program started operations in 2007 and uses Cessna planes flying from five major airports and covering most of the U.S. population, the publication confirmed, citing "people familiar with the operations."

The planes supposedly use devices created by Boeing that mimic the cell phone towers used by major telecommunications companies and trick mobile phones into revealing their registration data.

The devices, given the nickname "dirtboxes," are capable of collecting information from tens of thousands of cellphones in a single flight, the Journal reported.

A Justice Department official wouldn't confirm or deny the existence of such a program, saying that such discussion would allow criminal suspects to determine U.S. surveillance abilities. The official added that department agencies comply with federal law, including seeking court approval.

The program seems very similar to one used by the National Security Agency, which focuses on collecting phone records of millions of Americans in order to find a one person or a handful of people.

The device used in the program decides which phones belong to suspects and "lefts go" of non-suspect devices, according to the people familiar with the programs.

Though it can interrupt calls on some devices, officials have made software improvements to make sure it doesn't interrupt anyone contacting the 911 emergency number for assistance.

The program also bypasses telephone companies, letting authorities locate suspects directly, according to the Journal.

Christopher Soghoian, chief technologist at the American Civil Liberties Union, called the program "a dragnet surveillance program. It's inexcusable and it's likely, to the extent judges are authorizing it, they have no idea of the scale of it."

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