WASHINGTON, Dec. 30 -- U.S. Federal Aviation Administration (FAA) on Monday announced the selected six sites for researchers to test flying unmanned aircraft in general airspace.

The six test sites were located in the State of Alaska, Nevada, New York, North Dakota, Texas and Virginia, the agency said.

"These test sites will give us valuable information about how best to ensure the safe introduction of this advanced technology into our nation's skies," U.S. Transportation Secretary Anthony Foxx said in a statement.

Currently, the FAA mainly approves unmanned aircraft operations for public use and research purposes. But industry leaders want to expand the use of unmanned aircraft for commercial purposes.

Amazon Chief Executive Officer Jeff Bezos said earlier this month that the online retailer giant was testing the delivery of packages with drones, although it may take the FAA four or five years to set rules permitting the device.

The FAA has released an initial plan for integrating unmanned aircraft more broadly into U.S. airspace by September 2015 and these test sites will help conduct critical research into the certification and operational requirements to ensure the safe design and use of unmanned aircraft.

"Safety continues to be our first priority as we move forward with integrating unmanned aircraft systems into U.S. airspace," said FAA Administrator Michael Huerta. "We have successfully brought new technology into the nation's aviation system for more than 50 years, and I have no doubt we will do the same with unmanned aircraft."