South Korea's Unification Ministry says North Korea should not infringe the property rights of South Korean businesses at the shuttered Gaeseong Industrial Complex.

Earlier this week, Radio Free Asia reported the North has been secretly running 19 clothing factories in the joint North-South zone, which the South shut down February of last year in protest of Pyongyang's fourth nuclear test.

The North Korean propaganda portal Uriminzokkiri said Friday clothing factories in Gaesong will run more vigorously than ever, and that it is none of anyone's business.

It said that Washington and "its subordinates" may be attempting to scale up sanctions but they will not be able to stop the wheels of the factories turning and that they will clearly witness how workers are doing their jobs with confidence.

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