SEOUL, Jan. 12 (Yonhap) -- South Korea shut down a nuclear reactor Thursday due to a malfunctioning thermometer attached to the reactor's cooling pump, the government said.

The reactor at Wolseong Nuclear Power Plant, located some 400 kilometers southeast of Seoul, was automatically shut down at 4:24 a.m. due to the detected malfunction, according to the Ministry of Knowledge Economy.

The ministry said the stoppage of the reactor with generation capacity of 680,000 kilowatts will not affect the country's overall supply levels.

The Wolseong reactor is the third nuclear reactor to be shut down due to problems in less than a month since a reactor at a plant in Uljin, 330 kilometers southeast of Seoul, stopped operations on Dec. 13 due to what was later determined as a human mistake.

The two reactors shut down earlier have since resumed operations.