The Electronic Frontier Foundation said Wednesday it has sued the US Department of Homeland Security to obtain details about Predator drones on loan to domestic police departments.

EFF Internet freedom and privacy champions contended that they filed suit in federal court in San Francisco because the DHS failed to respond to a Freedom of Information Act request for the information.

A DHS division uses unmanned drones in the United States to patrol borders but reports indicate that missions are being flown on behalf of local and federal law enforcement agencies, according to the EFF.

"Drones are a powerful surveillance tool that can be used to gather extensive data about you and your activities," said EFF Staff Attorney Jennifer Lynch.

"The public needs to know more about how and why these Predator drones are being used to watch US citizens."

The EFF is also suing the US Federal Aviation Administration for the latest information about authorizations it has issued for public drone flights.