Operators of civilian drones, whose slated 2015 arrival in US skies has sparked privacy concerns, will have to indicate how they use collected data, regulators said Thursday.

Managers of six test sites for the unmanned aircraft must require every drone operator to have a "written plan for the operator's use and retention of data collected," the Federal Aviation Administration said in its first roadmap on the matter.

The FAA did not propose specific measures on privacy protection, recalling that operators must adhere to already existing laws.

And the agency recognized the "substantial debate and difference of opinion" about whether drone operations at the test sites will raise new privacy concerns.

Test site operators "must conduct an annual review of test site operations to verify compliance with stated privacy policy and practices and share those outcomes annually in a public forum," it added.

FAA chief Michael Huerta said some 7,500 small unmanned aircraft can be expected in national airspace in the next five years -- provided regulations are in place to handle them.

About 80 law enforcement agencies currently operate unmanned aircraft under special authorization.

The American Civil Liberties Union welcomed the FAA's acknowledgment that "the government must address privacy as drone use expands."

However, it urged that "procedural protections are followed by concrete restrictions on how data from drones can be used and how long it can be stored."

Michael Toscano, the president of the Association for Unmanned Vehicle Systems International (AUVSI) representing drone makers, welcomed the FAA roadmap.

He said any privacy laws must be platform neutral, treating manned and unmanned platforms the same.

According to AUVSI, the market for civilian drones will explode and lead to the creation of 100,000 jobs over the 10 years following their integration into US skies.