Growing uncertainty over the future of the joint-Korean Kaesong Industrial Complex is driving South Korean firms operating there back across the border.

Apparel manufacturer Skinnet on Monday became the first company to decide to stop operations at the complex. Stopping short of full withdrawal, some South Korean firms have already brought some of their facilities back to the South. Other firms have transferred production from Kaesong to China or Vietnam. The moves are seen as preparations for a full withdrawal from the complex.

North Korean workers work at a factory by a South Korean apparel company in the Kaesong Industrial Complex. /Reuters

According to the Unification Ministry, the export volume of the industrial park in January-April this year dropped 56.1 percent and output 6.6 percent year-on-year.

Cho Myung-chul, a senior researcher at the Korean Institute for International Economic Policy, said, "If wages at the Kaesong complex increase as to the level of China and more buyers ignore products from the complex, there will probably a domino effect of companies pulling out of Kaesong."