The authorities will take firm action against those found responsible for the equipment failure that caused a recent blackout in central Singapore, Senior Minister of State for Trade and Industry Koh Poh Koon said in a Facebook post yesterday.

"EMA has assured me that they will take firm action against any party found to be responsible for the disruption depending on the outcome of the investigations," Dr Koh said, referring to the Energy Market Authority (EMA).

EMA would also be working with SP Group and equipment suppliers to ensure that Singapore's power system remained reliable and robust, and that the chances of Thursday's incident happening again were minimised, he added.

Dr Koh visited SP Group's Kim Chuan substation, which contains transmission and distribution network equipment, and watched a demonstration of some maintenance-testing processes.

SP Group shared details of its regular maintenance regime, including regular testing of equipment and checks to monitor their condition.

On Thursday, electricity supply to parts of Bugis, City Hall, Marina and Somerset was disrupted for 12 minutes. The equipment failure also caused an electricity flashover, resulting in a fire at the Carlton Hotel, and affected seven MRT stations on the North East Line.