An official says South Korea's nuclear watchdog is investigating a forgery scandal that is forcing the shutdown of two reactors and sparked fears of unprecedented power shortages this winter.
Nuclear Safety and Security Commission spokeswoman Shim Eun-jung said Tuesday her agency is checking forged safety certificates and will invite civilian experts to participate.
South Korea announced Monday that it found five nuclear reactors running with falsely certified components. Officials say two reactors with the highest concentration of those parts have either shut down or will do so Tuesday.
About 30 percent of South Korea's electricity comes from nuclear plants and authorities warn electricity reserves could fall dangerously low if those parts aren't replaced by January. No radioactive leak has occurred.
Yonhap news agency says prosecutors are investigating the parts suppliers.