British authorities have recorded a three-fold increase in complaints about drones since 2015, when 1,237 complaints were recorded.

Armed police walk amongst shoppers along Oxford Street in London, Britain, in this file photograph dated December 23, 2015.  [Photo/Agencies]

As prices for drones have fallen, making them more accessible, complaints have risen. They range from intrusive flying over neighbors' homes to the use of drones to deliver drugs and illicit mobile phones over prison walls.

There have also been complaints about near misses with aircraft approaching London's main airports.

Anyone in the United Kingdom can legally control a drone, as long as it weighs less than 20 kilograms, and is not being used for commercial reasons. Flying drones within 150 meters of a congested zone and within 50 meters of a person, vessel, or vehicle is not allowed under UK legislation.

Operators must keep their drones within their line of sight, which effectively limits them to being within 122 meters vertically and 500 meters horizontally.

"As awareness of what drones are, and what they can do, continues to grow, police forces have seen increases in concerns and reports by the public," Assistant Chief Constable Steve Barry of the National Police Chiefs Council told the Daily Telegraph.

Professor David Dunn, of Birmingham University, said walls, hedges and fences had previously assured people of privacy on their own properties.

"That has changed because of drones," he said. "I've heard that burglars using drones is a big issue for police forces."

UK government ministers are now considering mandatory registration for newly purchased drones.

The use of drones for legal purposes has boomed in recent years. Drones were used to photograph every inch of China's Great Wall, and Amazon is experimenting with delivering parcels by drone in California.

The BBC now routinely uses drones in some reporting situations.

The cost of a small drone purchased from an online supplier can be as little as $50, and dealers report a surge in miniature "selfie" drones, in which the user can photograph themselves from a few meters away.

China's National Earthquake Response Service regularly uses drones to search for people trapped by tremors.Specially equipped drones with infrared technology can cover 5.2 square kilometers per trip and dramatically improve the time taken to locate survivors.