AUGUSTA, Maine — Unmanned, remotely controlled aircraft have become a daily tool of the military in Afghanistan, where they have proven invaluable in providing real-time information. But there is growing concern in Congress and among civil libertarians that law enforcement will want to use that technology more broadly at home.

“This is an issue of concern to a lot of members,“ Sen. Olympia Snowe said last week. “I supported an amendment to the farm bill that would have prohibited the Environmental Protection Agency from conducting aerial surveillance of farm operations. Unfortunately that failed to get the 60 votes necessary.”

The Republican senator said Congress has directed the Federal Aviation Administration to develop regulations for the use of drone aircraft for policing purposes, but Snowe says that use should be limited. She supports the use of drones for patrolling along border areas, something that has been underway for several years.

“I don’t support the broad use of these by government,” said Snowe, a member of the Senate Intelligence Committee.

Snowe said it is important that Congress consider legislation that would clearly spell out when and where law enforcement could use drones and not rely on rules from the FAA or other federal agencies.

The remote-controlled aircraft have become increasingly sophisticated and now include models that can hover over a location for hours and provide video and other surveillance data. They range from an aircraft that can carry a missile to hand-launched units.

Rep. Mike Michaud said he supports law enforcement use of drones, but only for limited purposes such as patrolling the border. He said there has been a lot of discussion among members about broad use by law enforcement agencies, which could pose serious privacy concerns.

“I have not heard of any real need that drones should be used broadly in the United States,” the Democrat who represents Maine’s 2nd District said last week. “I think there is a need on the border where we see illegal crossings and drugs being brought across the border.”

Michaud said he would need to be convinced that any additional use of the drone aircraft by law enforcement is warranted.

“There are real privacy concerns with using drones and we should make sure those are taken into account,” he said.

Some police agencies across the country are hoping the new federal rules being drafted will allow drone use by police in day-to-day operations. They argue there are savings in using remote-controlled aircraft rather than piloted aircraft or helicopters.

Shenna Bellows, executive director of the ACLU of Maine, said that is just what privacy advocates are worried about. She said the FAA rules could encourage increased use and that poses a whole range of privacy concerns.

“Drones should be prohibited from spying based on First Amendment protected activities,” she said earlier this week. “We oppose the congressional action telling the FAA to relax the drone rules.”

Bellows said the standard should be set high for when law enforcement can use drones for any purpose. She said there should be “specific and articulable” evidence that a crime has been committed before the remote-controlled aircraft can be used. She said drones have become so sophisticated, with cameras that can provide high-resolution pictures, that they pose a huge privacy risk.

Some drones also can be equipped with lenses to take pictures in very low light or in the dark with an infrared lens.

“Now that the genie is out of the bottle, the ACLU is calling for important safeguards on use of the drones,” she said. “We believe law enforcement should be required to get a warrant for drone use and that drone use should be geographically confined and time limited to emergency situations.”

Bellows said the drones should not become a tool that replaces a police officer on patrol. She is worried that the push in some states for use of drones will spread to Maine.

Col. Robert Williams, chief of the Maine State Police, the largest law enforcement force in the state, said his agency has no plans to acquire a drone.

“To my knowledge they are not being used by law enforcement in Maine,“ he wrote in an email.