South Korean companies failed to take all of their products and equipment out of the complex as North Korea expelled South Korean nationals one day after Seoul shut down the zone on Feb. 10, 2016, in response to North Korea's nuclear and missile tests.

The Ministry of Unification said that signs are detected that the position of vehicles belonging to local firms has changed though it cannot verify where or why they were moved.

"All remaining cars at the factory park belong to South Korean businessmen. North Korea should immediately stop using those vehicles without our authorization as the move is clearly an illegal act that violates local firms' property rights," Lee Eugene, a ministry spokesperson, told a regular press briefing.

The factory zone, once hailed as the symbol of inter-Korean reconciliation, had housed a total of 124 South Korean firms, hiring more than 54,000 North Korean workers to produce labor-intensive goods such as clothes and utensils.

In February, the ministry said that it had identified some "attempts" by North Korean authorities to sneakily take out and sell electric appliances like rice cookers from the complex.

The government said it had asked China to notify its people to not buy goods produced at the industry park if North Korea seeks to sell them. (Yonhap)