North Korea has blocked two South Korean officials from entering a jointly run factory park in the North over what it described as a conflict between the countries' management committees overseeing the complex.

An official from Seoul's Unification Ministry said Wednesday it isn't clear exactly why North Korea is preventing the officials from South Korea's management committee from entering the Kaesong industrial park. The official said South Korean employees of the factories are commuting normally across the border.

About 120 South Korean factories employ more than 53,000 North Koreans at the Kaesong complex, which opened in 2004. North Korea temporarily blocked South Korean workers from entering the factory park in 2009 to protest joint military drills by the United States and South Korea.