The airline will be cancelling 24 flights between Jan 23 and Feb 27, bringing to 43 the total number of cancelled flights on the route since Jan 14, when the first reduction took effect, to Feb 27.
Its Thailand general manager Ong Cheow Teck confirmed on Tuesday the further flight reduction was made "in view of the current situation in Bangkok".
The second round of reduction came as escalating political tensions, heightened by the start of Bangkok shutdown by anti-government movements last week, have shown more impacts on international arrivals to Thailand.
Early this month, the airline thought 19 flight cancellations on the Bangkok-Singapore route between Jan 14 and Feb 25 were enough.
The further cut has made it the international carrier which cancelled the most flights through Bangkok due to the ongoing the turmoil ahead of the Feb 2 nationwide election.
According to sources familiar with the carrier's operations, the further flight reduction came as travel demand by two major contributors to overall passengers on the route - Singaporeans and Chinese - have continued to dwindle, so much so that half the plane seats were empty.
Singapore Airlines' deployment of wide-body jets - Boeing 777 and Airbus 330 - on the Bangkok-Singapore route contributed to the excess capacity situation at the time of falling demand.
Those jets have an average seating capacity for 285 passengers.
The combined cancellation means that the carrier reduces its flight frequencies to an average of 4-5 flights per day in that timeframe.
Mr Ong told the Bangkok Post that affected customers have been informed via email and/or SMS and will be re-accommodated on other flights or refunded.
Sources said the growing violence related to the demonstrations, which have resulted in injuries and deaths, are chasing travellers away from Bangkok.
But international travellers are still coming to Thailand and many of them are skipping the capital and heading directly to destinations like Phuket, Chiang Mai and Koh Samui.
SilkAir, the regional wing of Singapore Airlines which operates direct flights from Singapore to Thai resort destinations including Phuket, Krabi, Koh Samui (in code share with Bangkok Airways) and Chiang Mai, continues its services as usual with "fairly good" load factor.