Devices that gather data from millions of mobile phones are being flown over the US by the government, according to the Wall Street Journal.
The "dirtbox" devices mimic mobile phone tower transmissions, and handsets transmit back their location and unique identity data, the report claims.
While they are used to track specific suspects, all mobile devices in the area will respond to the signal.
The US Justice Department refused to confirm or deny the report.
The Wall Street Journal said it had spoken to "sources familiar with the programme" who said Cessna aircraft fitted with dirtboxes were flying from at least five US airports.
The department said that it operated within federal law.
A dirtbox mimics the signals transmitted by mobile phone providers which handsets look to latch on to. When they do, they send their individual registration information and location.
While they are intended to be used to track an individual or small group, all phones within the area where they are operating will also be swept up in the surveillance.
They operate in the same way as Stingray, a more commonly known mobile phone surveillance too.