North Korea allowed two South Koreans involved in running the Kaesong industrial park back into North Korea on Friday. It gave no clear reason on why it decided to allow them to travel back to the industrial park, said Jeong Joon-Hee, a spokesman from Seoul's Unification Ministry.

One of the men allowed back to North Korea, Choi Sang-chul, was the vice chairman of Seoul's management committee that was overseeing the park. He had been involved in negotiations with the North over wages, taxes and fees. Jeong said Choi plans to visit the factory park on Monday.

There are about 120 South Korean companies employing more than 53,000 North Koreans in the Kaesong park. For the cash-strapped North, it has been a critical source of income since its establishment in 2004.

After negotiating for several months over wage levels for North Korean workers employed by South Korean companies at Kaesong, they agreed on a 5 percent increase in minimum wage in August.

The two sides are currently negotiating land usage fees that South Korean companies at Kaesong must pay to North Korea for 2015. Under a previous agreement, South Korean companies at Kaesong were exempted from land usage fees for 10 years through 2014.

The Koreas are still technically at war as the 1950-53 Korean War ended with an armistice, not a peace treaty.

av/sms (AP, AFP)