A North Korean defector was recently shot dead by the North\'s border guards on Chinese soil shortly after crossing a border river, a civic activist here claimed Monday, suggesting that the Pyongyang regime has toughened its crackdown on defectors. \"I witnessed on Oct. 22 a North Korean man shot to death by the North\'s guards, when he stepped onto a Chinese road after crossing the Amnok River near Hyesan in the northern province of Yanggang,\" Kim Yong-hwa, head of the North Korea Refugees Human Rights Association of Korea told Yonhap News Agency by phone. 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. The investigation has thus far confirmed that the group of defectors, believed to come from Seoncheon, North Pyeongan Province, carried with them a dog, an unprecedented move by defectors when seeking to avoid tight surveillance out of fear that the animals may make a noise, a government source told Yonhap News Agency. He declined to be identified. \"We were surprised to find the non-purebred dog in the five-ton wooden boat along with the defectors,\" the source said, adding the defectors are still being questioned about the motive for their decision. \"Chances are that the owners cherished their pet so much they couldn\'t leave it behind, or they took it as an emergency food supply to prepare for a longer-than-expected drift,\" he added.