Seoul has warned North Korea that it cannot restart operations at the Kaesong joint industrial complex, as it violates the property rights of South Korean firms which ran factories there.
The Unification Ministry issued the comment after North Korean propaganda outlets reported that the operations in the factory zone had been restarted.
A ministry official could not confirm this, but said that street lights and bus movement had been spotted.
The official added that the ministry will investigate further and may consider allowing local firms to enter the complex to check on their assets.
The complex, located near the inter-Korean border, hosted 124 South Korean firms from 2004, employing some 54-thousand North Korea workers. But it was shut down by Seoul in February 2016, after Pyongyang conducted nuclear and missile tests.