China deployed more than 1,200 troops and scrambled fighter jets in response to an unauthorised flight near Beijing airport by what turned out to be a mapping drone, state-run media reported Thursday.

Three men are being prosecuted over the incident, the China Daily said.

It cited prosecutors as saying that 1,226 military personnel, 123 military vehicles, 26 radar technicians, two fighter jets and two helicopters were sent into action after the aircraft was spotted on radar screens.

Police arrested two men as they flew the drone and a third confessed later, according to the paper, which is published by the government. All three men worked for an aviation technology company, the report said, and the 2.3-metre-long (seven-and-a-half-foot) drone was intended to be used for survey and mapping purposes.

China forbids any flights, manned or unmanned, without prior approval from the air force, civil aviation authorities and the local air traffic control bureau.

A New Zealand man was briefly detained by police in June after he flew a camera-equipped drone over the Forbidden City, a popular tourist site and former residence of China's emperors, which sits next to China's top-secret leadership compound.

The Beijing airport drone incident, which happened last December, caused 10 flights to be delayed, the newspaper added.