WASHINGTON (AP) — Federal regulators will require the registration of most drone aircraft to help track operators who flout safety rules and to encourage greater accountability, according to a drone industry official.

The Federal Aviation Administration is setting up a collaboration among government and industry officials and hobbyists to work out details of the registration system, according to the industry official, who wasn't authorized to speak publicly and spoke on condition of anonymity.

Those interests will decide which drones will require registration. Toys and small drones that don't present a safety threat are likely to be exempt. Drones that weigh only a pound or two or that can't fly higher than a few hundred feet are considered less risky. Heavier ones and those that can fly thousands of feet are more risky.

The FAA is scrambling to get registration rules in place before Christmas. The Consumer Electronics Association has forecast that 700,000 drones will be sold this holiday season.

Registering drones that could pose safety risks "makes sense, but it should not become a prohibitive burden for recreational users who fly for fun and educational purposes and who have operated harmoniously within our communities for decades," Dave Mathewson, executive director of the Academy for Model Aeronautics, said in a statement.

The FAA now receives about 100 reports a month from pilots who say they've seen drones flying near planes and airports, compared with only a few sightings per month last year. So far there have been no accidents, but agency officials have said they are concerned that even a drone weighing only a few pounds might cause serious damage if it is sucked into an engine or smashes into an airliner's windshield.

In cases where drones have crashed where they were not supposed to be flying — at crowded sports stadiums, for example — it has been difficult to find the operators.

The FAA signed an agreement last month with CACI International Inc., an information technology company in Arlington, Virginia, to test technology that could locate the operators of small drones that are flying illegally near airports. The technology would let the government track radio signals used to operate drones within a 5-mile radius and identify the operator's location.

___

Follow Joan Lowy on Twitter at http://www.twitter.com/AP_Joan_Lowy