FBI Director Robert Mueller said the law enforcement agency uses unmanned drones within the country for surveillance in certain difficult cases.
Mueller told the Senate Judiciary Committee yesterday that drones are used by the FBI in a "very, very minimal way and very seldom."
He did not say how many unmanned surveillance vehicles (UAVs) the FBI has or how often they have been used.
The official said drones are useful in hostage and barricade situations because they operate more quietly and are less visible than traditional aircraft such as helicopters.
The FBI said it used a UAV earlier this year to monitor the situation where a boy was held hostage in a bunker in Alabama.
FBI spokesman Paul Bresson said their use allows "us to learn critical information that otherwise would be difficult to obtain without introducing serious risk to law enforcement personnel."
Mueller's comments come as the Obama administration is trying to wriggle out of the political fallout from the public disclosure of surveillance programmes, which has triggered new debate over reach of national security vs. Privacy rights.
President Barack Obama has assured Americans the government is not listening to their phone conversations or reading their e-mail.
