Prosecutors said Friday they have detained a former chief of the country's state-run nuclear power plants operator on suspicion of bribery as part of their probe into the corruption scandal over nuclear reactors.

Kim Jong-shin, who headed the Korea Hydro and Nuclear Power (KHNP), was arrested on late Thursday after the task force of the Busan District Prosecutor's Office in the southeastern port city secured evidence that Kim had accepted bribes from one of the company's contractors.

The arrest came one month after the prosecutors raided the KHNP's headquarters and offices. Prior to the raid, the operation of six nuclear reactors was suspended -- including three newly built reactors -- after they were found to have been supplied with substandard control cables under falsified warranties from the local supplier, JS Cable, among others.

The 68-year-old Kim served as the chief of KHNP from April 2007 until May 2012, while JS Cable had supplied faulty cables for two nuclear reactors since 2008.

"He is suspected of accepting bribes from the agency's contractor. More investigations are needed to see if his alleged bribery has something to do with fake parts," a prosecutor said, without elaborating further.

JS Cable, affiliated with LS Group, the country's major electricity materials supplier, was found to have fabricated the test results for cables that failed to meet international standards for capacity to withstand changes in voltage and pressure.

The latest shutdown follows a scandal that erupted late last year involving more than 13,000 substandard parts supplied under fake quality warranties for over 10 years.

South Korea operates 23 reactors, supplying about 30 percent of its total electricity consumption. (Yonhap News)