Singapore, Jun 25 (IANS): Unauthorised drone activities and also the bad weather caused several flight delays and diversions at Singapore's Changi airport, authorities said on Tuesday.

The Civil Aviation Authority of Singapore (CAAS) said that approximately 15 departures and three arrivals were delayed, while seven flights were diverted on Monday night, reports Channel News Asia.

"As a precautionary measure, arrival and departure flights were carefully regulated for short periods of time between 8.07 p.m. and 9.07 p.m.," said the CAAS in a statement.

On June 19, 38 flights were affected when drones were sighted around the airport.

The CAAS statement said that investigations were ongoing.

It also said that it takes a serious view of errant operations of unmanned aircraft which may pose threats to aviation or endanger the personal safety of others, and will not hesitate to take enforcement action.

Offenders could face a fine of up to S$20,000 ($14,784) or a jail term of up to 12 months.

In Singapore, drones are prohibited from flying within 5 km of an airport without a permit, reports Channel News Asia.

Drones are increasingly disrupting flights at airports around the world.

London's Gatwick was paralysed for 36 hours last December following repeated drone sightings, with tens of thousands of passengers affected.