City Hall on Monday announced a ban on the use of drones without prior approval, declaring them a threat to privacy and security, highlighted on Saturday when a drone flew over the Royal Palace and alarmed Queen Mother Norodom Monineath.

The increasing use of drones by television companies and enthusiasts prompted municipal authorities to issue an injunction to protect the city’s residents from invasions of their privacy and the dangers posed by drones’ misuse, according to a statement released by City Hall.

“In cases where their use is considered necessary, permission must first be obtained from City Hall authorities,” it says, explaining that violators would be punished.

Municipal spokesman Long Dimanche said that on Saturday, a German man guided a drone over the grounds of the Royal Palace while the Queen Mother was in the courtyard, but he denied that the ban was purely in response to the incident.

“This is one reason, but there are many other reasons,” the spokesman said. “Drones are using cameras and video to take pictures of people without permission and invading privacy, but the measure is also to protect against terrorists using drones to attack the government.”

Mr. Dimanche added that the ban applied to both private and commercial use but should be understood as a regulation, and not as an outright prohibition on drone use, while the sale and purchase of drone technology would be unaffected.

Many countries require approval for the commercial use of drones, or unmanned aerial vehicles, which usually involves applying for a license from a state aviation regulator. But while City Hall’s ban covers both personal and commercial use, it offered no guidelines or criteria for the types of flights it is likely to approve.

Ngeth Moses, a communications coordinator for the Community Legal Education Center and citizen-journalism instructor, called City Hall’s ban impractical and unnecessary.

“City Hall’s response should have been more reasonable, as drones have built-in technology that can pre-program them to avoid certain no-fly zones, that areas such as the Royal Palace could easily be assigned,” said Mr. Moses, who is also a member of the Professional Society of Drone Journalists, founded in 2011.

Carlyle Thayer, a Southeast Asia expert at the Australian Defense Force Academy, said there was a compelling need for governments to regulate the use of drones in urban areas in the interest of public safety.

“Regulations to control drones, however, are unlikely to deter terrorists and criminals from using them if it suits their purposes,” he said by email.

“It is also likely that government officials prefer to control emerging technologies to their advantage and to deny the use of these technologies to their opponents. If drones were to be used by the media to report on civil unrest, Cambodian government officials definitely would want to restrict their usage,” he said.

Amanda King, spokeswoman for the Cambodia Center for Independent Media, said she did not believe the media or rights groups were being specifically targeted but said the new rule needed to be expanded upon.

“The government has not done a good enough job of explaining the ban or how people will be punished,” she said. “Drones are such an effective means of monitoring human rights and civil disturbances, so it could have a disconcerting effect.”