Japanese and South Korean media are speculating that a high-ranking North Korean official, possibly even leader Kim Jong Un, is visiting China after an airliner from the North landed in the Chinese port city of Dalian.

The South's official Yonhap News Agency said the plane arrived Monday amid tight security. Japanese broadcaster NHK ran a picture of the Air Koryo plane that it said had been taken Tuesday afternoon at Dalian airport.

There are no regularly scheduled flights between North Korea and Dalian, although North Koreans are frequent visitors and its port has been instrumental in two-way trade.

Kim visited China in March for the first time since taking power six years ago, a trip that was publicly confirmed by the sides only after he had returned to North Korea.