By Sohee Kim and Meeyoung Cho
SEOUL (Reuters) - Seoul prosecutors have launched an investigation into a leak of non-critical data at South Korea's nuclear power operator, the prosecutors' office said on Sunday, as worries mount about nuclear safety and potential cyberattacks from North Korea.
An official with the prosecutors' office confirmed media reports that they had traced the location of an IP address linked to the leak and had dispatched investigators to the site.
She said she could not comment further on the case while an investigation was under way, including on whether North Korea might be behind the leak.
Concern over potential cyberattacks from North Korea has got worldwide attention since the hacking of computers at Sony Pictures, which the United States has blamed on Pyongyang.
North Korea has denied the accusations and called for a joint investigation into the incident with Washington.
Diagrams of several of South Korea's 23 nuclear reactors have been posted on a Twitter account since the data leak last week, which included employees' personal records, blueprints of nuclear plant equipment, electricity flow charts and estimates of radiation exposure among local residents. There was no evidence, however, that the nuclear control systems were hacked.
Korea Hydro and Nuclear Power Co Ltd (KHNP), operator of the nuclear plants and part of state-run utility Korea Electric Power Corp, said it had stepped up its monitoring and was on a heightened level of alert for cyberattacks.
"We are making utmost efforts, working closely with the government to assess the data leak at certain nuclear power plants, which adds to social unease," the nuclear plant operator KHNP said in a statement on Sunday.
The KHNP said in a separate statement that it will conduct large-scaled drills at four nuclear power plant complexes against cyberattacks on Monday and Tuesday.
Worries about nuclear safety in South Korea, which relies on nuclear reactors for a third of its electricity and is the world's fifth-largest nuclear power user, have mounted since the 2011 Fukushima disaster in Japan and a domestic scandal in 2012 over the supply of reactor parts with fake security certificates.
(Editing by Edmund Klamann, Greg Mahlich)