The FBI has used drones in a limited number of cases for surveillance over American soil.
FBI director Robert Mueller has told a United States Senate committee the agency has very few drones and has used them very seldom.
Mr Mueller described the drone use in testimony on Wednesday to the US Senate Judiciary Committee, where he was questioned on the matter by Senator Chuck Grassley (Republican, Iowa).
"I will tell you that our footprint is very small," said Mr Mueller, who is retiring in September after 12 years as director of the bureau.
He said drones were used in "particular incidents where you need the capability", adding he was unsure how long images captured by the drones were kept.
But he acknowledged that the FBI is only in the initial stages of developing drone policies.
According to media reports at the time, a surveillance drone was used during a stand-off with a man in Alabama who shot a school bus driver and took a five-year-old boy hostage in February.
In March, Senator Rand Paul (Republican, Kentucky) raised concerns about the use of drones against Americans.
The BBC reports he demanded a pledge that the federal government would not use such aircraft in the US to kill terror suspects who are American citizens.
Senator Paul spoke on the issue for nearly 13 hours on the Senate floor, in a tactic known as a filibuster, to delay the nomination of a new CIA chief.