A top South Korean official on Sunday blamed hot weather and inaccurate reports by public officials for the nation's worst-ever blackout and vowed to punish those responsible.
More than 1.6 million homes, including 400,000 in Seoul, were affected by Thursday's rare power outage which disconnected mobile phone networks and closed bank cash dispensers.
Knowledge Economy Minister Choi Joong-Kyung said officials had under-estimated overall power demand for September despite the unusually hot weather, and miscalculated available supply on the day of the blackout.
The Korea Power Exchange (KPE) failed to take into account the five hours it takes for power plants to heat up and get ready for actual distribution, over-estimating supply by several million kilowatts on Thursday, he said.
"The temperature continued to rise and power demand kept increasing in the meantime… I was reported about the situation too late to try anything," Choi told reporters.
It was unclear whether the officials intentionally over-estimated the reserves on the day of the power outage.
The blackouts sparked chaos across the country, with many people trapped in halted elevators, vehicles caught in gridlock with traffic lights out and factory assembly lines stopped.
No deaths or injuries were reported.
Power cuts are rare in South Korea, a country with high-quality infrastructure. Newspapers said the scale of disruption was unprecedented.
The five-hour power outage sparked criticism of the government for failing to heed weather forecasts and neglecting to give prior notice of cuts.
"I feel tremendous responsibility for the crisis and will do my best to prevent a recurrence… and hold those responsible accountable," Choi said.
A special team of officials would launch an investigation and receive complaints beginning this week from those affected seeking compensation, he added.
