Still, as the call was prepared elaborately, the police and the country‘s spy agency concluded that it is hard to regard it as a simple prank call and set up a task force team at one of Seoul’s police stations.

According to police, the call is believed to have been made from Laos, but they are still investigating the exact location.

They are also looking into whether any other sounds can be detected in the call.

“(We are) sure that the call was from abroad,” an official said. “Once the exact location is confirmed, (we) are planning to demand cooperation from Interpol.”

Airports have strengthened inspection and immigration control but airline services are operating normally as there is no concrete threat of explosion, authorities said. (Yonhap)