The FBI uses drones in domestic surveillance operations in a “very, very minimal way,” Director Robert S. Mueller III said Wednesday.

Appearing before the Senate Judiciary Committee, Mueller acknowledged for the first time that the FBI uses “very few” drones in a limited capacity for surveillance.

“It’s very seldom used and generally used in a particular incident when you need the capability,” Mueller said when asked about the bureau’s use of pilotless aircraft with surveillance capabilities. “It is very narrowly focused on particularized cases and particularized needs.”

Mueller’s remarks about the FBI’s use of drones — and the regular use of the vehicles by other law enforcement agencies — come as lawmakers and civil liberties groups are raising concerns about the reach of the government in the wake of the disclosure of two highly classified National Security Agency surveillance programs.

Leaks by former intelligence contractor Edward Snowden to The Washington Post and Britain’s Guardian newspaper unveiled surveillance programs that sweep up telephone call data from millions of U.S. citizens, as well as Internet traffic, that the Obama administration says involves foreigners based outside the United States who are suspected of plotting terrorist attacks.

Lawmakers, including Senate Judiciary Committee Chairman Patrick J. Leahy (D-Vt.), and civil liberties groups have raised concerns about the impact on privacy of drones used by federal law enforcement agencies. The Homeland Security Department regularly deploys drones to oversee the southern border.

“This is a burgeoning concern for many of us,’ Sen. Mazie Hirono (D-Hawaii) said of drone use by the government as well as by private companies or individuals.

The Federal Aviation Administration estimates there may be about 10,000 active commercial drones in five years. Bills have been introduced in at least 18 states to limit or regulate such aircraft, according to the National Conference of State Legislatures.

Leahy said during a March hearing on drones that he was ‘‘convinced that the domestic use of drones to conduct surveillance and collect other information will have a broad and significant impact on the everyday lives of millions of Americans going forward.’’

Mueller said the FBI is in ‘‘the initial stages’’ of formulating privacy guidelines related to its drone use.

‘‘There are a number of issues related to drones that will need to be debated in the future,’’ Mueller said. ‘‘It’s still in its nascent stages, this debate.’’

Homeland Security Secretary Janet Napolitano said Saturday in a Bloomberg Television interview that the operation of unmanned aircraft makes ‘‘our forces on the ground more effective’’ and that privacy concerns are regularly weighed and addressed by an office within the department.

— Bloomberg News