The Homeland Security Department’s border drones program costs far more than the government estimates, helps in the arrests of just a fraction of the number of people trying to cross the border illegally and flies far fewer hours than the government claims, an internal watchdog asserted in a report released Tuesday.

Inspector General John Roth said in his report that the Predator B drones flown along the border by Customs and Border Protection are “dubious achievers.”

Customs and Border Protection doesn’t have any performance measures, so the agency can’t prove that the program is effective, it said.

CBP planned to operate four 16-hour drone patrols a day, for about 23,290 total flight hours during the 2013 budget year that ended Sept. 30, 2013. But Roth’s audit found that the planes were actually in the air for about 5,100 hours, or roughly 22 percent of the planned flight time.

Drones have also led to relatively few apprehensions of people crossing the border illegally. In the two busiest Border Patrol sectors, Tucson, Arizona, and Texas’ Rio Grande Valley, drones accounted for only about 2,270 of the more than 275,000 apprehensions in 2013.

CBP spokesman Carlos Lazo said the agency disagrees with the report’s findings and said auditors don’t appear to fully understand the program, including future expansion plans. He said while CBP is authorized to add drones to the fleet, there are no immediate plans to do so.

CBP has nine drones flying along the Mexican and Canadian borders as well as coast lines in Florida, Texas and Southern California. A 10th drone was downed over the Pacific Ocean last year after suffering technical problems. Roth said while the agency hopes to add about 14 aircraft in the coming years the $443 million the agency plans to spend on expanding the fleet could be better spent on manned aircraft and ground surveillance.

The drone fleet also doesn’t patrol the entire Southwest border, as Homeland Security has previously reported, Roth found. Instead, drone operations are focused along about 100 miles of border in Arizona and about 70 of border in Texas.

Roth’s review of the program also found significant disparities in cost estimates. Auditors concluded that the drone program cost roughly $62.5 million, or about $12,255 an hour, in 2013. CBP estimated a cost of $2,468 per flight hour, but that price didn’t include operating costs including pilots, equipment and overhead.

Roth recommended, among other things, that the department reconsider expanding the drone program.

(AP)