Seletar Airport was closed on Thursday morning to all departing and arriving flights as a result of prolonged poor visibility caused by the haze.
The current closure will last until 11pm on Thursday, and may be extended subject to visibility conditions.
The visibility on Thursday was fluctuating between 700m and 1,200m. This is below the airport's minimum operating requirement of 1,500m. As the airport operates under visual meteorological conditions, it could not accept aircraft arrivals and departures as pilots would not have a clear view of the runway.
During the closure period, two arrivals were diverted to other airports, and eight departures were cancelled.
The Civil Aviation Authority of Singapore (CAAS) and Changi Airport Group are closely monitoring the visibility conditions before reopening Seletar Airport for flight operations.
Over at Changi Airport, CAAS told The Straits Times on Wednesday night that controllers have increased the separation between flight takeoffs and landings as a precaution, and there have been no significant delays so far.