The internal watchdog for the Homeland Security Department says the agency's unmanned drones it flies along the border are far more expensive and flying far fewer hours than the government says.

Inspector General John Roth says in a new report released Tuesday that the Predator B drones are "dubious achievers." Although U.S. Customs and Border Protection says each drone costs $2,648 per hour to fly, the actual cost is more than $12,000 per hour. And the report says drones have assisted in fewer than 2 percent of arrests of people crossing the border illegally.

The agency did not immediately comment on the criticism.

The report recommends that Customs and Border Protection abandon its plans to spend $443 million more on additional aircraft and put those funds to better use.