A special train, thought to be transporting North Korean leader Kim Jong-il, passed over an Amnok River (Yalu River) bridge around 6:15 a.m. Monday and entered Dandong, China.

South Korean sources say the North Korean train made a 15-minute stop at Dandong station before heading for the Chinese city of Shenyang.

Although it has yet to be confirmed whether Kim was on board the passenger train, a high-ranking South Korean official says it is highly likely that he was.

In a phone interview with KBS, the official said Kim was most likely on the train since security was lifted when the train left Dandong.

Another official says confirmation about whether Kim has entered China will come in a few hours.

If Kim is found to have entered China, the trip comes amid heightened tension on the Korean Peninsula over the sinking of South Korea's “Cheonan” naval vessel.