Taiwan suffered a huge power blackout on Tuesday evening that hit businesses and residential homes, affecting close to seven million households on the heavily industrialised island amid sweltering heat.
The outage left millions of homes without power and hit offices and factories on the island of nearly 24 million people, but appeared to have a limited impact on businesses, including some of the world's leading technology manufacturers.
Taiwan Semiconductor Manufacturing (TSMC), the world's largest contract chip maker and a major supplier to Apple, said its operations were not affected, as did electronics manufacturer Pegatron.
ChipMOS Technologies Inc said the outage had not had a big impact on its operations. Its shares fell 2 per cent in early trade, lagging a flat broader market.
Power had been fully restored across the island by Wednesday, local media said.
Residents complained as temperatures hovered around 32C, while the blackout caused havoc as restaurants and small businesses were left without power, traffic lights stopped working and elevators stalled.
The power outage was caused by a human technical error at state-owned gas supplier CPC that affected the operations of a state-owned Taiwan Power power plant in northwestern Taoyuan, the two companies said at a news conference on Tuesday evening.
Taiwan Power's outage at its Taoyuan plant caused six generators to stop working, resulting in a extensive blackout across Taiwan, the company said.
The president Tsai Ing-wen apologised on her Facebook page for the blackout, describing electricity supply as a national security issue.
Relevant government departments needed to quickly explain why a single event could cause such large damage across the country's electricity system, she said.
"We must reform the system. I will make this an important point for thorough inspection reforms in the future."
Taiwan's minister of economics Affairs Chih-Kung Lee had offered to resign over the incident, which was accepted by the premier Lin Chuan, the government said.
Lee's formal resignation letter was expected later this week, it said. If he steps down as expected, he will do so just over a year after assuming office.
CPC said it accepted responsiblity for the outage and was investigating the cause. The blackout was the country's most severe since the 1999 Jiji earthquake, Taiwan Power Co said.