The ministry in charge of inter-Korean affairs said it did not detect any meaningful change in radiation density levels in the Yellow Sea, after a claim by a satellite expert that North Korea released unpurified radioactive wastewater.

Speaking to reporters on Tuesday, an official at Seoul's unification ministry said officials, in cooperation with related agencies, are closely keeping tabs on the North's nuclear activities, such as the uranium plant in Pyongsan, North Pyongan Province.

The official said the ministry is in talks with the agencies regarding the direction of the government's response measures as the matter directly concerns public health and safety.

According to Daily NK, an outlet dedicated to the North, the expert, Jeong Seong-hak, claimed that radioactive wastewater from the Pyongsan plant had entered waters near Gagnhwa Island following an analysis of satellite imagery from the U.S. Environmental Systems Research Institute.