The government has worked out a draft bill to ban drones from flying over crowded urban areas as well as during nighttime, sources close to the matter said Thursday, a move taken in response to concerns that the unmanned aircraft could be used for terrorist attacks.

The government is seeking to pass the bill to revise the Civil Aeronautics Law during the ongoing Diet session, which would also impose up to ¥500,000 in fines for people who violated the rules.

The government has decided to take a tough stance against the use of drones, after a small one with a minuscule amount of radiation was found on the roof of the prime minister's office building in April. A man was arrested for allegedly maneuvering the drone.

Under the draft bill, the government defined unmanned aircraft, such as drones, as vehicles that can be remotely commanded or automatically operated.

No-fly zones would include crowded residential areas, altitudes that might affect the operation of airplanes and areas near airports.

Operators would only be allowed to use the unmanned aircraft from sunrise to sunset and should always visually check the situation of the area where the drone is flying. They would also be prohibited from delivering explosive devices or other items that could do harm to people or objects, according to the draft bill.

But there could be exceptions, such as when police use drones for accident investigations or rescue missions.