Some 37 flights were delayed and operations of one of Changi Airport's two runways were affected overnight after unauthorised drones were spotted flying in the vicinity of the airport over the last two days.
The Civil Aviation Authority of Singapore (CAAS) said in a statement yesterday: "To ensure the safety of aircraft operations and passengers, the operations of one runway were suspended for short periods of time between 11pm on June 18 and 9am on June 19."
It noted that Changi Airport continued to operate with one runway while operations on the other runway were suspended.
The agency added that 37 scheduled departure and arrival flights were delayed as a result, with one arrival flight being diverted to Kuala Lumpur.
A multi-agency team that includes the CAAS, Changi Airport Group, Singapore Armed Forces and the police has been activated for search-and-locate operations.
Investigations are ongoing, said the CAAS, which added that the authorities take a serious view of the errant operation of drones which could pose a threat to aviation or personal safety.
Under the Unmanned Aircraft (Public Safety and Security) Act, the flying of drones within 5km of airports or military airbases, or at altitudes above 200 feet (61m), without a permit is an offence.
Those found guilty of violating these regulations face a fine of up to $20,000 or up to 12 months in jail, or both.
Drones have disrupted civil aviation elsewhere.
In December, unauthorised drone activity disrupted flights at London's Gatwick Airport for three days, affecting about 140,000 passengers and 1,000 flights.
And earlier this week, flights at the East Midlands airport in Britain were also disrupted due to drones.
In January, Senior Minister of State for Transport Lam Pin Min told Parliament that there had been eight reports of unauthorised drones flying within 5km of Changi Airport over the past three years, though none of these cases involved intrusions into the airport.
Government Parliamentary Committee for Transport member Lim Biow Chuan told The Straits Times last night that he hoped the authorities would be able to identify and take action against the drone operators.
The MP for Mountbatten added: "The mindless actions of such irresponsible people have wasted people's time and caused inconvenience to innocent passengers."