Around 18 departures and arrivals were delayed and seven flights were diverted from the global transit hub due to "bad weather and unauthorised drone activities", the Civil Aviation Authority of Singapore said in a statement on June 25.
A similar incident involving drone flying affected 38 flights on Tuesday and Wednesday (June 18-19) last week.
Authorities are investigating.
A surge in the availability of drones has become an increasing security concern for airports around the world.
In December, drone sightings caused three days of travel chaos at London's Gatwick airport, resulting in the cancellation or diversion of about 1,000 flights at an estimated cost of more than GBP50 million (US$64 million).
