South Korean firms operating in the inter-Korean Gaeseong Industrial Complex are growing anxious as Pyongyang has prolonged its closure of the South-North border for the fourth day Monday.

South Korean companies in the industrial park are concerned that the travel ban could lead to a variety of problems, including cancellations of orders and major glitches in transporting materials. The companies are also concerned that they might see shortages of food and gas for heating.

Earlier on Sunday, an association representing some of the 130 South Korean companies in Gaeseong issued a statement urging Pyongyang to immediately normalize inter-Korean border passage. The association also called on Pyongyang to guarantee that it would not block the inter-Korean border in the future.

In Seoul, Unification Minister Hyun In-taek expressed deep regret over the North’s blockade, saying the government is watching the situation closely and will respond appropriately.