The Amnok River, or the Yalu River in Chinese, separates the two communist allies.

"I believe the man was a North Korean, as the North's guards would not shoot a Chinese person on Chinese soil," he said. "Some 30 minutes after his death, several Chinese security officials approached the scene to investigate."

Kim said he personally saw the incident while touring the border town with a Chinese tour guide at the request of a broadcasting company, and he had his tour guide record what happened with his cellphone.

The strong and rare response to the assumed defection is telltale evidence that the reclusive North Korean regime has strengthened efforts to stem the escape of its people and stop the influx of foreign influences out of fear they could pose a threat to leader Kim Jong-il's plan to transfer power to his heir apparent Kim Jong-un.

The 69-year-old leader named Jong-un vice chairman of the Central Military Commission of the North's ruling Workers' Party and a four-star general last year in the clearest sign yet to make his youngest son believed to be in his late 20s the next leader.

To thwart defection, the North has installed surveillance cameras and reinforced barbed wire in its northern border areas close to China including Hyesan and Sinuiju after leader Kim called for a thorough inspection of residents during his trip to Sinuiju in July, according to sources.

The border areas have served as key routes through which a stream of North Koreans continue to flee to China for eventual defection to South Korea, home to more than 22,000 North Korean refugees.

Meanwhile, a group of 21 North Koreans found drifting aboard a boat off South Korea's west coast late last month has come under questioning by officials here after they expressed their wish for remaining in the South.