South Korean groups to cut energy use after shortage warning South Korea's biggest manufacturers plan to cut electricity consumption this summer amid fears of power shortages after a corruption scandal prompted the shutdown of nuclear reactors. The government last week said three of the country's 23 nuclear reactors would be suspended indefinitely after they were found to be using cables with forged safety certificates. Another seven reactors are also out of service for routine maintenance, and are expected to come back online over the next three months. The scandal threatens to cast a shadow over South Korea's reputation as an exporter of nuclear energy technology. In 2009, South Korea signed a $20bn deal to build four nuclear plants in the United Arab Emirates, and it is seeking further agreements with Finland and Vietnam. Seoul regularly urges big companies to restrict electricity usage during the harsh winter and hot summer, when power demand surges. But the latest shutdowns in the nuclear sector, which accounts for about a third of South Korea's electricity capacity, have prompted unusually strong warnings. On Friday, the government said the suspensions would lead to "unprecedented" shortages this summer. It unveiled financial incentives to urge households to cut consumption and ordered public offices to reduce usage by up to 20 per cent. On Monday, the Korea Power Exchange, which manages the electricity market, issued a national warning after the amount of spare capacity fell below 4.5m kW, about 5 per cent of normal supply. Large manufacturers said this week that they would respond to the appeal to curtail consumption during the summer, when demand typically spikes due to air conditioning usage. LG Chem, South Korea's largest chemicals group, said it would start operating some production lines during non-peak hours. It is difficult to resume production if our petrochemical lines are stopped due to a blackout. That would incur huge damage on production," the company said. Posco, the world's fourth-largest steelmaker by output, said it already generates more than 70 per cent of its own energy requirements, but would increase that proportion while adjusting its operation schedules during times of peak demand. Its rival Hyundai Steel said it would cut output in response to requests from the state-controlled Korea Electric Power Company. Other groups, including Samsung Electronics, Hyundai Motor and LG Electronics, also said they would comply with the request to conserve energy. The revelation about the forged safety certificates at the nuclear plants has drawn public outcry and condemnation from President Park Geun-hye. Two other nuclear plants were shut over similar concerns in November, but they have since reopened. "The scandal will certainly undermine South Korea's efforts to expand nuclear exports, because its main selling point so far has been the high operating ratio of the country's domestic plants," said Lee Won-hee, a researcher at the Samsung Economic Research Institute. Kim Joong-kyum, former Kepco chief executive, resigned soon after the scandal broke in November. In April, prosecutors indicted two workers at a Kepco subsidiary and 11 employees of parts suppliers for bribery, supplying fake parts and other corruption. Suh Kyun-ryul, a professor of atomic engineering at Seoul National University, said the problem stemmed from "cosy relations" between companies and the nuclear regulator. "The suppliers have taken advantage of the lack of supervision by authorities," said Mr Suh. It won't be easy to regain the public trust unless this culture of corruption is changed. Additional reporting by Kang Buseong